CVE-2025-25291 | ruby-saml vulnerable to SAML authentication bypass due to DOCTYPE handling (parser differential)

Exp

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.

Published: 2025-03-12 Last update: 2025-11-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-25291 is rated High Exploit Risk (90.7/100): CVSS Critical severity, with high exploitation likelihood (EPSS 20.84%, 96th percentile). 2 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +7.00% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-25291

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-25291

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-20 13.85% 20.84% +7.00%
2 2026-01-06 17.71% 13.85% -3.87%
3 2025-12-27 — 17.71% —

Full EPSS history (38 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-25291

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.3 4.0 CRITICAL
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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:H)
High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2025-25291

GitHub Security Advisory for CVE-2025-25291

GHSA-4vc4-m8qh-g8jm · Severity: critical · Ecosystem: rubygems — Ruby SAML allows a SAML authentication bypass due to DOCTYPE handling (parser differential)

OS Trackers for CVE-2025-25291

vendor priority summary link
debian not yet assigned CVE-2025-25291 not yet assigned priority: Debian including 1 source packages (ruby-saml), 2 status rows across 2 suites (bookworm, bullseye): open 1, resolved 1. https://security-tracker.debian.org/tracker/CVE-2025-25291
ubuntu medium CVE-2025-25291 medium priority: Ubuntu including 1 source packages (ruby-saml), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): released 6, ignored 2, DNE 1. https://ubuntu.com/security/CVE-2025-25291

Affected software / configurations for CVE-2025-25291

Vendor Product Version Raw CPE
omniauth omniauth_saml < 1.10.6 cpe:2.3:a:omniauth:omniauth_saml:*:*:*:*:*:ruby:*:*
omniauth omniauth_saml >= 2.0.0, < 2.1.3 cpe:2.3:a:omniauth:omniauth_saml:*:*:*:*:*:ruby:*:*
omniauth omniauth_saml >= 2.2.0, < 2.2.3 cpe:2.3:a:omniauth:omniauth_saml:*:*:*:*:*:ruby:*:*
onelogin ruby-saml < 1.12.4 cpe:2.3:a:onelogin:ruby-saml:*:*:*:*:*:*:*:*
onelogin ruby-saml >= 1.13.0, < 1.18.0 cpe:2.3:a:onelogin:ruby-saml:*:*:*:*:*:*:*:*
netapp storagegrid — cpe:2.3:a:netapp:storagegrid:-:*:*:*:*:*:*:*

References for CVE-2025-25291

URL Tags
https://about.gitlab.com/releases/2025/03/12/patch-release-gitlab-17-9-2-released Patch
https://github.blog/security/sign-in-as-anyone-bypassing-saml-sso-authentication-with-parser-differentials Exploit Third Party Advisory
https://github.com/SAML-Toolkits/ruby-saml/commit/e76c5b36bac40aedbf1ba7ffaaf495be63328cd9 Patch
https://github.com/SAML-Toolkits/ruby-saml/commit/e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97 Patch
https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.12.4 Release Notes
https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.18.0 Release Notes
https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-4vc4-m8qh-g8jm Vendor Advisory
https://github.com/omniauth/omniauth-saml/security/advisories/GHSA-hw46-3hmr-x9xv Vendor Advisory
https://portswigger.net/research/saml-roulette-the-hacker-always-wins Exploit Third Party Advisory
https://securitylab.github.com/advisories/GHSL-2024-329_GHSL-2024-330_ruby-saml Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/04/msg00011.html
https://news.ycombinator.com/item?id=43374519 Issue Tracking
https://security.netapp.com/advisory/ntap-20250314-0010/ Third Party Advisory
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