{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-102266", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-09-28T20:11:16.658Z", "datePublished": "2026-09-28T20:21:26.164Z", "dateUpdated": "2026-09-29T19:35:42.049Z"}, "containers": {"cna": {"title": "PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation", "problemTypes": [{"descriptions": [{"cweId": "CWE-347", "lang": "en", "description": "CWE-347: Improper Verification of Cryptographic Signature", "type": "CWE"}]}], "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"}}], "references": [{"name": "https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r"}, {"name": "https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c", "tags": ["x_refsource_MISC"], "url": "https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c"}, {"name": "https://github.com/jpadilla/pyjwt/releases/tag/2.14.0", "tags": ["x_refsource_MISC"], "url": "https://github.com/jpadilla/pyjwt/releases/tag/2.14.0"}], "affected": [{"vendor": "jpadilla", "product": "pyjwt", "versions": [{"version": ">= 2.13.0, < 2.14.0", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-09-28T20:21:26.164Z"}, "descriptions": [{"lang": "en", "value": "PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0."}], "source": {"advisory": "GHSA-9j54-fg26-wv3r", "discovery": "UNKNOWN"}}, "adp": [{"references": [{"url": "https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-09-29T19:28:36.086597Z", "id": "CVE-2026-102266", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-29T19:35:42.049Z"}}]}}

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{"bugzilla": {"description": "pyjwt: pyjwt: Authentication bypass via empty HMAC key acceptance", "id": "2542671", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2542671"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-347", "details": ["A flaw was found in pyjwt. A remote attacker can forge authentication tokens and bypass security controls by signing tokens with an empty key. When verifying tokens against a JSON Web Key (JWK) set that contains an empty Hash-based Message Authentication Code (HMAC) key, the library fails to enforce key-length validation. This allows an attacker to generate valid tokens carrying arbitrary claims to gain unauthorized access."], "name": "CVE-2026-102266", "package_state": [{"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "jaeger", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "llvm21", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "rust", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "swift-lang", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-09-28T20:21:26Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-102266\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-102266\nhttps://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c\nhttps://github.com/jpadilla/pyjwt/releases/tag/2.14.0\nhttps://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r"], "threat_severity": "Important"}