Medium [CVE-2026-75509] Issuer-validation bypass via array-valued claims
This medium-severity Red Hat Linux advisory covers CVE-2026-75509 affecting Lightspeed Core, Migration Toolkit for Applications 8, OpenShift Lightspeed.
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Summary
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.
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.
Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N). Weakness: CWE-480.
Affected Red Hat products: Lightspeed Core; Migration Toolkit for Applications 8; OpenShift Lightspeed; Red Hat Ansible Automation Platform 2; Red Hat Enterprise Linux command line assistant; Red Hat OpenShift Virtualization 4; Red Hat Satellite 6. Red Hat lists Red Hat Hardened Images as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
- < 1.7.3
Official advisory · high-confidence parse· fetched 41 minutes ago·verify at source
- 1.7.3
Official advisory · high-confidence parse· fetched 41 minutes ago·verify at source
Mitigation
Upgrade to a fixed release: 1.7.3. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 41 minutes ago·verify at source
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