Vulnerability-Lookup

UBUNTU-CVE-2026-25537 (CVE-2026-25537)

Vulnerability from osv_ubuntu – Published: 2026-02-04 22:15 – Updated: 2026-05-20 15:26 – Source website

Details

jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library’s internal parsing mechanism marks the claim as “FailedToParse”. Crucially, the validation logic treats this “FailedToParse” state identically to “NotPresent”. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like “Not Before” checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0.

Severity

5.5 (Medium)


                    
                      CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

7.5 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-25537	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-25537	REPORT
	https://github.com/Keats/jsonwebtoken/commit/abbc…	REPORT
	https://github.com/Keats/jsonwebtoken/security/ad…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-jsonwebtoken-dev",
            "binary_version": "8.3.0-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "rust-jsonwebtoken",
        "purl": "pkg:deb/ubuntu/rust-jsonwebtoken@8.3.0-3?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.3.0-1",
        "8.3.0-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-jsonwebtoken-dev",
            "binary_version": "8.3.0-5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "rust-jsonwebtoken",
        "purl": "pkg:deb/ubuntu/rust-jsonwebtoken@8.3.0-5?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.3.0-5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-jsonwebtoken-dev",
            "binary_version": "9.3.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "rust-jsonwebtoken",
        "purl": "pkg:deb/ubuntu/rust-jsonwebtoken@9.3.1-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.3.0-5",
        "9.3.1-1"
      ]
    }
  ],
  "aliases": [],
  "details": "jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library\u2019s internal parsing mechanism marks the claim as \u201cFailedToParse\u201d. Crucially, the validation logic treats this \u201cFailedToParse\u201d state identically to \u201cNotPresent\u201d. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like \u201cNot Before\u201d checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0.",
  "id": "UBUNTU-CVE-2026-25537",
  "modified": "2026-05-20T15:26:05Z",
  "published": "2026-02-04T22:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-25537"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-25537"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-25537"
  ]
}

CVE-2026-25537 (GCVE-0-2026-25537)

Vulnerability from cvelistv5 – Published: 2026-02-04 21:31 – Updated: 2026-02-05 20:52

Title

jsonwebtoken has Type Confusion that leads to potential authorization bypass

Summary

Severity

5.5 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-02-05 20:52 UTC

CWE

CWE-843 - Access of Resource Using Incompatible Type ('Type Confusion')

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/Keats/jsonwebtoken/security/ad…	x_refsource_CONFIRM
https://github.com/Keats/jsonwebtoken/commit/abbc…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
Keats	jsonwebtoken	Affected: < 10.3.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-25537",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-05T20:52:41.199183Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-02-05T20:52:48.021Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "jsonwebtoken",
          "vendor": "Keats",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 10.3.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library\u2019s internal parsing mechanism marks the claim as \u201cFailedToParse\u201d. Crucially, the validation logic treats this \u201cFailedToParse\u201d state identically to \u201cNotPresent\u201d. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like \u201cNot Before\u201d checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.5,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-843",
              "description": "CWE-843: Access of Resource Using Incompatible Type (\u0027Type Confusion\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-04T21:31:53.511Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc"
        },
        {
          "name": "https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01"
        }
      ],
      "source": {
        "advisory": "GHSA-h395-gr6q-cpjc",
        "discovery": "UNKNOWN"
      },
      "title": "jsonwebtoken has Type Confusion that leads to potential authorization bypass"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-25537",
    "datePublished": "2026-02-04T21:31:53.511Z",
    "dateReserved": "2026-02-02T19:59:47.374Z",
    "dateUpdated": "2026-02-05T20:52:48.021Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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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.

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UBUNTU-CVE-2026-25537 (CVE-2026-25537)

CVE-2026-25537 (GCVE-0-2026-25537)

Tags

Sightings

Nomenclature

Related by attack behaviour