HTTP::Headers::ActionPack versions before 0.10 for Perl allow CPU exhaustion via Accept-Language…

Why it is Yellow

• CVSS 7.5 high
• Remotely exploitable without logging in

References

• https://github.com/robrwo/perl-HTTP-Headers-ActionPack/commit/77f0deb23f3de872c2e64befd72750e0f0f4bec9.patch
• https://metacpan.org/release/RRWO/HTTP-Headers-ActionPack-0.10/changes
• http://www.openwall.com/lists/oss-security/2026/10/23/27

Original description

HTTP::Headers::ActionPack versions before 0.10 for Perl allow CPU exhaustion via Accept-Language ranges matched as regular expressions. _language_match interpolates each Accept-Language range into the pattern `/^$range\-/i` without escaping it, so regular expression syntax in the header reaches the regex engine. A 12-byte range such as `(a?|b?){26}z` backtracks for seconds, and each increment of the quantifier doubles the time. An invalid range such as `(` fails to compile. A remote attacker can exhaust CPU, or make choose_language die, in any application that passes an untrusted Accept-Language header to it.