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  4. CVE 2026 75509 joserfc claim validation bypass via array typed
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Back to active CVEs
Medium · CVSS 6.5CVE-2026-75509

joserfc claim-validation bypass via array-typed single-string claims (iss/sub/jti)CVE-2026-75509

Answer in brief

CVE-2026-75509 records a Medium severity (CVSS 6.5) vulnerability in joserfc claim-validation bypass via array-typed single-string claims (iss/sub/jti). The current sources do not mark it as known exploited. The current feed maps authlib/joserfc (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 24, 2026Updated Sep 9, 2026Source checked Oct 9, 2026First seen by HOL Aug 24, 2026Material review Sep 9, 2026
Upstream Advisory

Key facts

Risk
Medium · CVSS 6.5
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps authlib/joserfc (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
authlib/joserfcgeneric<1.7.31.7.3

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for authlib/joserfc.
  2. 2Review the reported fix. Update authlib/joserfc to 1.7.3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Aug 24, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Sep 9, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 24, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
Upstream source description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Unauthenticated JSON API Authorization Bypass Vulnerability in TP-Link Tapo C325WBSame generic ecosystem
  • Unauthenticated RTSP Tunnel Denial-of-Service Vulnerability in TP-Link Tapo C325WBSame generic ecosystem
  • Predictable Media Stream Pre-Shared Key Vulnerability in TP-Link Tapo C325WBSame generic ecosystem
  • Eog: eog: arbitrary code execution via heap buffer overflow in png metadata readerSame generic ecosystem
  • fast-jwt treats raw public JWK JSON as an HMAC secret, enabling HS256 token forgerySame generic ecosystem
  • Hazelcast: Authorization bypass in IMap Predicates APISame generic ecosystem

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-290, CWE-345
Source
CVE List V5
Source checked
Oct 9, 2026
References
2 linked sources
Open source record