CVE-2026-114615 (GCVE-0-2026-114615)

Vulnerability from cvelistv5 – Published: 2026-10-22 21:10 – Updated: 2026-10-22 21:10
VLAI
Title
Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys
Summary
Authlib is a Python library which builds OAuth and OpenID Connect servers. From 1.3.1 until 1.9.0, OctKey.import_key() checks asymmetric-key markers only at byte zero while Authlib's PEM loaders accept leading whitespace, comments, or a byte-order mark. In deployments that use the documented mixed algorithm registry and already configure verification with PEM or certificate bytes containing such a prefix, an unauthenticated attacker who knows those same public-key bytes can use them as an HMAC secret and forge HS256 tokens with arbitrary identity or authorization claims. This is a bypass of the remediation for CVE-2024-37568. The module-level jwt object reaches OctKey.import_key() in authlib/jose/rfc7518/oct_key.py, where POSSIBLE_UNSAFE_KEYS fails to identify prefixed asymmetric key material. This issue is fixed in version 1.9.0.
Severity
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-184 - Incomplete List of Disallowed Inputs
  • CWE-347 - Improper Verification of Cryptographic Signature
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7664 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
authlib authlib Affected: >= 1.3.1, < 1.9.0
guessed Create a notification for this product.
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{
  "containers": {
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        {
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          "vendor": "authlib",
          "versions": [
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              "status": "affected",
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          "lang": "en",
          "value": "Authlib is a Python library which builds OAuth and OpenID Connect servers. From 1.3.1 until 1.9.0, OctKey.import_key() checks asymmetric-key markers only at byte zero while Authlib\u0027s PEM loaders accept leading whitespace, comments, or a byte-order mark. In deployments that use the documented mixed algorithm registry and already configure verification with PEM or certificate bytes containing such a prefix, an unauthenticated attacker who knows those same public-key bytes can use them as an HMAC secret and forge HS256 tokens with arbitrary identity or authorization claims. This is a bypass of the remediation for CVE-2024-37568. The module-level jwt object reaches OctKey.import_key() in authlib/jose/rfc7518/oct_key.py, where POSSIBLE_UNSAFE_KEYS fails to identify prefixed asymmetric key material. This issue is fixed in version 1.9.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
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              "type": "CWE"
            }
          ]
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        {
          "descriptions": [
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              "cweId": "CWE-347",
              "description": "CWE-347: Improper Verification of Cryptographic Signature",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-22T21:10:02.023Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
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          "name": "https://github.com/authlib/authlib/security/advisories/GHSA-7vr2-2fgp-9w7p",
          "tags": [
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          "url": "https://github.com/authlib/authlib/security/advisories/GHSA-7vr2-2fgp-9w7p"
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        {
          "name": "https://github.com/authlib/authlib/pull/945",
          "tags": [
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          "tags": [
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          ],
          "url": "https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf"
        },
        {
          "name": "https://github.com/authlib/authlib/releases/tag/v1.9.0",
          "tags": [
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          "url": "https://github.com/authlib/authlib/releases/tag/v1.9.0"
        }
      ],
      "source": {
        "advisory": "GHSA-7vr2-2fgp-9w7p",
        "discovery": "UNKNOWN"
      },
      "title": "Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-114615",
    "datePublished": "2026-10-22T21:10:02.023Z",
    "dateReserved": "2026-10-21T20:34:25.600Z",
    "dateUpdated": "2026-10-22T21:10:02.023Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
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        "affected": [
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              {
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                "vendor": "authlib",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003e= 1.3.1, \u003c 1.9.0"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Authlib is a Python library which builds OAuth and OpenID Connect servers. From 1.3.1 until 1.9.0, OctKey.import_key() checks asymmetric-key markers only at byte zero while Authlib\u0027s PEM loaders accept leading whitespace, comments, or a byte-order mark. In deployments that use the documented mixed algorithm registry and already configure verification with PEM or certificate bytes containing such a prefix, an unauthenticated attacker who knows those same public-key bytes can use them as an HMAC secret and forge HS256 tokens with arbitrary identity or authorization claims. This is a bypass of the remediation for CVE-2024-37568. The module-level jwt object reaches OctKey.import_key() in authlib/jose/rfc7518/oct_key.py, where POSSIBLE_UNSAFE_KEYS fails to identify prefixed asymmetric key material. This issue is fixed in version 1.9.0."
          }
        ],
        "id": "CVE-2026-114615",
        "lastModified": "2026-10-22T22:18:04.257",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 7.4,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
                "version": "3.1"
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              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-22T22:18:04.257",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/authlib/authlib/pull/945"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/authlib/authlib/releases/tag/v1.9.0"
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            "source": "security-advisories@github.com",
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          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Received",
        "weaknesses": [
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              {
                "lang": "en",
                "value": "CWE-184"
              },
              {
                "lang": "en",
                "value": "CWE-347"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
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    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-10-23T01:11:52+00:00",
      "cve": "CVE-2026-114615",
      "id": "CVE-2026-114615",
      "initial_release_date": "2026-10-22T21:10:02.023000+00:00",
      "product_status:known_affected": "11",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "authlib: Authlib: Authentication bypass via improper asymmetric key validation",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-114615.json",
      "version": "3"
    }
  }
}



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