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Fencer Vulns
high 8.6

CVE-2025-27773 json

SimpleSAMLphp SAML2 library has incorrect signature verification for HTTP-Redirect binding

published 2025-03-11 19 mo ago modified 2026-09-10 1 mo ago also EUVD-2025-7804 , GHSA-46r4-f8gj-xg56

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

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.

Patch / fix

  • packagist simplesamlphp/saml2 4.17.0, 5.0.0-alpha.20
  • packagist simplesamlphp/saml2-legacy 4.17.0
  • simplesamlphp saml2 4.17.0, 5.0.0-alpha.20
  • simplesamlphp Debian 12 1.19.7-1+deb12u2
  • simplesamlphp Debian 14 1.19.7-2

debian advisories DEBIAN-CVE-2025-27773

  • simplesamlphp Ubuntu 24.04 LTS 1.19.7-1+deb12u1ubuntu0.1
  • simplesamlphp Ubuntu Pro 16.04 LTS 1.14.0-1ubuntu2+esm1
  • simplesamlphp Ubuntu Pro 18.04 LTS 1.15.3-1ubuntu0.1~esm1
  • simplesamlphp Ubuntu Pro 20.04 LTS 1.18.4-1ubuntu0.1~esm1
  • simplesamlphp Ubuntu Pro 22.04 LTS 1.19.1-1.1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2025-27773

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
GitHub 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
packagist simplesamlphp/saml2
<4.17.0
>=5.0.0-alpha.1, <5.0.0-alpha.20
4.17.0
5.0.0-alpha.20
packagist simplesamlphp/saml2-legacy
<4.17.0
4.17.0

Affected products

  • simplesamlphp saml2

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.