ubuntu-cve-2026-25537
Vulnerability from osv_ubuntu
Published
2026-02-04 22:15
Modified
2026-05-20 15:26
Summary
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
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"
  ]
}



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