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Fencer Vulns
critical 9.8

CVE-2025-25291 in the critical feed json

ruby-saml vulnerable to SAML authentication bypass due to DOCTYPE handling (parser differential)

published 2025-03-12 19 mo ago modified 2026-09-08 2 mo ago also BIT-gitlab-2025-25291 , EUVD-2025-6415 , GHSA-4vc4-m8qh-g8jm

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
21.0%
EPSS 21.0% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known

Summary

ruby-saml provides security assertion markup language (SAML) single sign-on (SSO) for Ruby. An authentication bypass vulnerability was found in ruby-saml prior to versions 1.12.4 and 1.18.0 due to a parser differential. ReXML and Nokogiri parse XML differently; the parsers can generate entirely different document structures from the same XML input. That allows an attacker to be able to execute a Signature Wrapping attack. This issue may lead to authentication bypass. Versions 1.12.4 and 1.18.0 fix the issue.

Patch / fix

  • rubygems ruby-saml 1.12.4, 1.18.0
  • bitnami gitlab 17.9.2
  • onelogin ruby-saml 1.12.4, 1.18.0
  • omniauth omniauth_saml 1.10.6, 2.1.3, 2.2.3
  • gitlab gitlab 17.7.7, 17.8.5, 17.9.2
  • gitlab gitlab_enterprise 17.7.7, 17.8.5, 17.9.2
  • ruby-saml Ubuntu Pro 18.04 LTS 1.7.2-1ubuntu0.1~esm2
  • ruby-saml Ubuntu Pro 20.04 LTS 1.11.0-1ubuntu0.1+esm1
  • ruby-saml Ubuntu Pro 22.04 LTS 1.13.0-1ubuntu0.1+esm1
  • ruby-saml Ubuntu Pro 24.04 LTS 1.15.0-1ubuntu0.24.04.1+esm1

ubuntu advisories UBUNTU-CVE-2025-25291

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
total
Assessed
19 mo ago

Exploit prediction

20.96% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.blog https://github.blog/security/sign-in-as-anyone-bypassing-saml-sso-authentication-with-parser-differentials referenced PoC, tagged "exploit" by a source, unverified
  • portswigger.net https://portswigger.net/research/saml-roulette-the-hacker-always-wins referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
rubygems ruby-saml
<1.12.4
>=1.13.0, <1.18.0
1.12.4
1.18.0
bitnami gitlab
<17.9.2
17.9.2

Affected products

  • SAML-Toolkits ruby-saml

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature
  • CWE-436 Interpretation Conflict
Technology feeds

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.