Vulnerability-Lookup

ubuntu-cve-2026-84394

Vulnerability from osv_ubuntu

Published

2026-09-04 00:00

Modified

2026-09-04 00:00

Summary

Details

fast-uri accepts a host that contains an unbalanced or misplaced authority bracket without reporting an error. A host that starts with an opening bracket but does not end with a closing bracket is neither validated as an IP literal nor canonicalized as a domain name, so parse() returns it as the host with error undefined, while Node's URL and the HTTP clients built on it resolve the same string to a different host. An application that reads the parsed host to make a host decision, such as an SSRF denylist, a redirect allowlist, or proxy routing, and then passes the original URL to an HTTP client evaluates its policy against a string that is not the host the request reaches. The same host is carried through normalize, equal, and resolve. This affects fast-uri versions 2.4.5, 3.1.6, and 4.1.3, and is fixed in 2.4.6, 3.1.7, and 4.1.4, where parse() reports a malformed host for any host that contains a bracket but is not a valid IPv6 literal.

Severity

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-2026-84394	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-84394	REPORT
	https://github.com/fastify/fast-uri/security/advi…	REPORT
	https://cna.openjsf.org/security-advisories.html	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-ajv",
            "binary_version": "5.0.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "node-ajv",
        "purl": "pkg:deb/ubuntu/node-ajv@5.0.0-1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "5.0.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-ajv",
            "binary_version": "6.10.2-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "node-ajv",
        "purl": "pkg:deb/ubuntu/node-ajv@6.10.2-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "6.10.2-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-ajv",
            "binary_version": "6.12.6-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "node-ajv",
        "purl": "pkg:deb/ubuntu/node-ajv@6.12.6-3?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "6.12.6-2",
        "6.12.6-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-ajv",
            "binary_version": "8.12.0~ds+~2.1.1-4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "node-ajv",
        "purl": "pkg:deb/ubuntu/node-ajv@8.12.0~ds+~2.1.1-4?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "6.12.6-3",
        "8.12.0~ds+~2.1.1-4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-ajv",
            "binary_version": "8.17.1~ds+~3.0.1+~3.1.0-4build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "node-ajv",
        "purl": "pkg:deb/ubuntu/node-ajv@8.17.1~ds+~3.0.1+~3.1.0-4build1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.12.0~ds+~2.1.1-5",
        "8.17.1~ds+~3.0.1+~3.1.0-2",
        "8.17.1~ds+~3.0.1+~3.1.0-4build1"
      ]
    }
  ],
  "aliases": [],
  "details": "fast-uri accepts a host that contains an unbalanced or misplaced authority bracket without reporting an error. A host that starts with an opening bracket but does not end with a closing bracket is neither validated as an IP literal nor canonicalized as a domain name, so parse() returns it as the host with error undefined, while Node\u0027s URL and the HTTP clients built on it resolve the same string to a different host. An application that reads the parsed host to make a host decision, such as an SSRF denylist, a redirect allowlist, or proxy routing, and then passes the original URL to an HTTP client evaluates its policy against a string that is not the host the request reaches. The same host is carried through normalize, equal, and resolve. This affects fast-uri versions 2.4.5, 3.1.6, and 4.1.3, and is fixed in 2.4.6, 3.1.7, and 4.1.4, where parse() reports a malformed host for any host that contains a bracket but is not a valid IPv6 literal.",
  "id": "UBUNTU-CVE-2026-84394",
  "modified": "2026-09-04T00:00:00Z",
  "published": "2026-09-04T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-84394"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-84394"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/fastify/fast-uri/security/advisories/GHSA-58mr-gqgx-xq4g"
    },
    {
      "type": "REPORT",
      "url": "https://cna.openjsf.org/security-advisories.html"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "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-2026-84394"
  ]
}

CVE-2026-84394 (GCVE-0-2026-84394)

Vulnerability from cvelistv5 – Published: 2026-09-02 20:25 – Updated: 2026-09-03 13:14

Title

fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority

Summary

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-03 13:14 UTC

CWE

CWE-436 - Interpretation Conflict

Assigner

openjs redhat root

References

2 references

URL	Tags
https://github.com/fastify/fast-uri/security/advi…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
fast-uri	fast-uri	Affected: 2.4.5 , < 2.4.6 (semver) Unaffected: 2.4.6 (semver) Affected: 3.1.6 , < 3.1.7 (semver) Unaffected: 3.1.7 (semver) Affected: 4.1.3 , < 4.1.4 (semver) Unaffected: 4.1.4 (semver)

Credits

YashvantHange mcollina UlisesGascon

Show details on NVD website

JSON

To clipboard

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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.

Detection rules are retrieved from Rulezet.

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.