SB2026053110 - Insufficient verification of data authenticity in SimpleSAMLphp

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Main Vulnerability Database SB2026053110

SB2026053110 - Insufficient verification of data authenticity in SimpleSAMLphp

Published: May 31, 2026

Security Bulletin ID SB2026053110
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Insufficient verification of data authenticity (CVE-ID: CVE-2026-49284)

CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear


The vulnerability allows a remote user to bypass authentication and authorization checks.

The vulnerability exists due to insufficient verification of data authenticity in the SAML SP ACS path when processing a valid response from an unexpected trusted IdP with an unsigned Response/InResponseTo and no SubjectConfirmationData/InResponseTo in the signed assertion. A remote user can obtain a signed assertion from a lower-trust trusted IdP and submit it to satisfy SP state created for a different expected IdP to bypass authentication and authorization checks.

The issue is relevant in multi-IdP deployments where authorization decisions depend on the selected or expected IdP.


Remediation

Install update from vendor's website.

References