CVE-2026-75509
Description
A flaw was found in joserfc, a Python library for JSON Object Signing and Encryption (JOSE) standards. A remote attacker could exploit a vulnerability in the JWTClaimsRegistry by crafting a JSON Web Token (JWT) with an array-valued issuer (iss) claim. This flaw allows the attacker to bypass the intended issuer validation, potentially leading to impersonation or unauthorized access.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
Understanding the Weakness (CWE)
Other
Technical Impact: Alter Execution Logic
This weakness can cause unintended logic to be executed and other unexpected application behavior.
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