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Public proof of conceptFix available

CVE-2025-27773

A public proof of concept exists; no exploitation attested.

  • Published2025-03-11
  • Fixed in5.0.0-alpha.20 · 4.17.0
  • WeaknessCWE-347

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2025-03-1119:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-27773?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-27773?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV
simplesamlphp/saml2
BranchAffectedFixed in
5.0≥ 5.0.0-alpha.1, < 5.0.0-alpha.205.0.0-alpha.20
4.17< 4.17.04.17.0
simplesamlphp/saml2-legacy
BranchAffectedFixed in
4.17< 4.17.04.17.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update simplesamlphp/saml2 to 5.0.0-alpha.20 · 4.17.0

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionpoc2025-03-11
  • OpenCVESSVC decisionpoc—
  • CNACVSS 3.18.6read 2026-10-23
  • CNAweakness (CWE)CWE-347read 2026-10-23
  • FIRST EPSSEPSS score0.4 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Published
2025-03-11
Last Modified
2026-06-17
NVD status
Deferred

Frequently asked questions

What is CVE-2025-27773?

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.

Is CVE-2025-27773 actively exploited?

A proof-of-concept exploit exists for CVE-2025-27773, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2025-27773?

CVE-2025-27773 has a CVSS v3 base score of 8.6 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N.

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