CVE-2026-87081

Name	CVE-2026-87081
Description	Net::IDN::UTS46 versions before 2.590 for Perl allow CPU exhaustion via quadratic punycode encoding of an overlong label before the length check in to_ascii. to_ascii punycode encodes each label and only then applies the 63-byte DNS limit. encode_punycode in both backends follows the sample implementation in RFC 3492, whose outer loop runs once per distinct non-ASCII code point and scans the whole input each round, so a label of distinct non-ASCII characters costs the square of its length before the limit rejects it. Every ASCII conversion in the distribution, including domain_to_ascii and email_to_ascii, goes through to_ascii.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1148729

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libnet-idn-encode-perl (PTS)	bookworm	2.500-3	vulnerable
	trixie	2.500-5	vulnerable
	forky, sid	2.502-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libnet-idn-encode-perl	source	(unstable)	(unfixed)			1148729

Notes

https://lists.security.metacpan.org/cve-announce/msg/43753018/
Fixed by: https://github.com/robrwo/Net-IDN-Encode/commit/5ac3315131264670efcd3a29857b651506dfee8e (v2.590-TRIAL)
Fixed by: https://github.com/robrwo/Net-IDN-Encode/commit/ea34f812d7dc67f3b211f4d92e74c6a7e24d764a (v2.590-TRIAL)