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PyJWT CVE-2026-102272

| EUVDEUVD-2026-88540 HIGH
Improper Verification of Cryptographic Signature (CWE-347)
2026-09-28 GitHub_M GHSA-r6x4-923q-g947
Authentication Bypass Python Jwt Attack Pyjwt Jpadilla
7.4
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
7.4 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
vuln.today AI
5.9 MEDIUM

Attacker needs no auth (PR:N) but a specific mixed-algo/raw-JWK config plus BOM manipulation (AC:H); primary impact is token forgery/auth-bypass so I:H, C:N/A:N.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.4 HIGH
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

4
POC Analysis Generated
Sep 28, 2026 - 23:24 vuln.today
Patch available
Sep 28, 2026 - 22:02 EUVD
Analysis Generated
Sep 28, 2026 - 21:15 vuln.today
CVE Published
Sep 28, 2026 - 20:36 cve.org
HIGH 7.4

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 206 pypi packages depend on pyjwt (131 direct, 76 indirect)

Ecosystem-wide dependent count for version 2.13.0.

DescriptionCVE.org

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0.

Articles & Coverage 1

News 13 New Python Vulnerabilities - 2 Critical, 11 High, 2 With POC Sep 29, 2026

AnalysisAI

Token forgery in PyJWT 2.13.x lets unauthenticated remote attackers mint tokens that the library will accept as authentic: when a public JWK is prefixed with a UTF-8 byte-order mark and passed directly as the raw HMAC secret inside a mixed-algorithm verification path, HMACAlgorithm.prepare_key fails to recognize the material as an asymmetric key and uses the publicly known JWK bytes as the shared secret, so anyone who knows the public key can sign arbitrary claims that verify successfully. The flaw carries an assessed CVSS of 7.4 (integrity-only impact, AC:H, PR:N) and per our independent assessment is conditionally scoped: it requires PyJWT 2.13.0 through 2.13.x, an application that permits HMAC alongside asymmetric algorithms, code that hands a raw public JWK to prepare_key instead of loading it via PyJWK/HMACAlgorithm.from_jwk, and BOM-prefixed key material. …

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Vulnerability AssessmentAI

Exploitation Exploitation requires all of: the application runs PyJWT 2.13.0 through 2.13.x (fixed in 2.14.0); a mixed-algorithm verification path that permits HMAC (e.g., HS256) alongside asymmetric algorithms; the application passing an asymmetric PUBLIC JWK directly as the raw key argument to HMACAlgorithm.prepare_key rather than loading it via PyJWK/HMACAlgorithm.from_jwk; and the public JWK being prefixed with a UTF-8 byte-order mark (or otherwise BOM/encoding-mangled) so the raw-JWK detector fails to identify it as JSON. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a real but conditionally-scoped algorithm-confusion flaw in PyJWT, a ubiquitous Python JWT library. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patch: upgrade PyJWT to 2.14.0, the version in which HMACAlgorithm.prepare_key normalizes BOM-prefixed and deeply nested key material before the raw-JWK check; the fix is visible in commit 180783930de91876bc0d601f826a1f2956057291 and the release at https://github.com/jpadilla/pyjwt/releases/tag/2.14.0, with details in advisory GHSA-r6x4-923q-g947. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Vendor-released patch: 2.14. …

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Performance Computing 12 Not-Affected
SUSE Linux Enterprise Micro 5.5 Not-Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 Not-Affected
SUSE Linux Enterprise Module for Python 3 15 SP7 Not-Affected

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CVE-2026-102272 vulnerability details – vuln.today
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