6.3 Medium

Crass: A large number of adjacent CSS comments can trigger a SystemStackError

CVE-2026-61847

Impact When the :preservecomments option is not enabled (which is the default behavior), Crass discards CSS comments by recursively consuming the next token. An attacker who provides a stylesheet containing a very large number of adjacent comments can cause excessive recursion and trigger a SystemStackError. Patches This is fixed in Crass 1.0.7, which no longer recurses when discarding comments. Workarounds Set the :preservecomments option to true if this is acceptable to your use case (recursion doesn't occur when comments are preserved).

Assessment

CVSS: 6.3 (v4.0)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 29 October 2026
Last updated: 29 October 2026
Affected: rubygems · crass
Weakness: CWE-674

CVSS vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

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