CVE-2025-27773HIGH 8.6EPSS p21.1%

CVE-2025-27773CVE-2025-27773

Description

The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.17.0 and 5.0.0-alpha.20, there is a signature confusion attack in the HTTPRedirect binding. An attacker with any signed SAMLResponse via the HTTP-Redirect binding can cause the application to accept an unsigned message. Versions 4.17.0 and 5.0.0-alpha.20 contain a fix for the issue.

Scoring

CVSS 3.18.6 (HIGH)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
EPSS0.30% probability of exploitation · percentile 21.1% · 2026-06-18T12:00:27Z
Published2025-03-11
Last modified2026-04-15

Underlying weaknesses· 1

CWE-347

References

  1. https://github.com/simplesamlphp/saml2/blob/9545abd0d9d48388f2fa00469c5c1e0294f0303e/src/SAML2/HTTPRedirect.php#L104-L113
  2. https://github.com/simplesamlphp/saml2/blob/9545abd0d9d48388f2fa00469c5c1e0294f0303e/src/SAML2/HTTPRedirect.php#L178-L217
  3. https://github.com/simplesamlphp/saml2/commit/7867d6099dc7f31bed1ea10e5bea159c5623d2a0
  4. https://github.com/simplesamlphp/saml2/security/advisories/GHSA-46r4-f8gj-xg56
  5. https://lists.debian.org/debian-lts-announce/2025/05/msg00013.html

1

TypeTargetConfidenceTier
WeaknessImproper Verification of Cryptographic Signaturecwe-3470%live

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Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.