AIKIDO-2026-10868
symfony/yaml is vulnerable to Regular Expression Denial of Service (ReDoS)
37
Low Risk
This Affects:
symfony/yamlTL;DR
Parser::cleanup() uses regular expressions with overlapping quantifiers while stripping YAML directives and markers. Crafted leading YAML content can trigger catastrophic backtracking. Pre-fix applications that parse untrusted YAML can spend excessive CPU during cleanup. The fix rewrites the cleanup expressions with unambiguous, non-backtracking patterns.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range.
Background info
symfony/yaml is vulnerable to Regular Expression Denial of Service (ReDoS) in versions 0.0.1 - 5.4.51, 6.0.0 - 6.4.39, 7.0.0 - 7.4.11 and 8.0.0 - 8.0.11.
How to fix this
Upgrade the symfony/yaml and/or symfony/symfony library to the patch version.
Links
GitHub Releases
github.com/symfony/yaml/releases/tag/v8.0.12github.com/symfony/symfony/releases/tag/v5.4.52github.com/symfony/symfony/releases/tag/v6.4.40github.com/symfony/symfony/releases/tag/v7.4.12github.com/symfony/symfony/releases/tag/v8.0.12
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