CVE-2026-12087

Socket versions before 2.041 for Perl have an out-of-bounds heap read. In Socket.xs, pack_ip_mreq_source() checks the length of its source argument before the argument is read, so the check tests the byte length carried over from the preceding multiaddr argument instead. Both addresses occupy a 4-byte field, so a valid multiaddr lets a source of any length pass the check, and the source is then copied into the 4-byte imr_sourceaddr field with a fixed-size copy. A source shorter than 4 bytes is not rejected, and the copy reads up to 3 bytes past the end of its buffer. Calling pack_ip_mreq_source() with a source value shorter than 4 bytes copies adjacent heap memory into the returned packed structure.

• libsocket-perl 2.041-1 (bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1146063) [trixie] - libsocket-perl 2.038-1+deb13u1 [bookworm] - libsocket-perl (Minor issue; up-to-3-byte heap over-read, only reachable when a script passes attacker-controlled source to pack_ip_mreq_source()) [bullseye] - libsocket-perl (Minor issue; up-to-3-byte heap over-read, only reachable when a script passes attacker-controlled source to pack_ip_mreq_source()) [experimental] - perl 5.44.0-1
• perl 5.42.3-1 (bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1140152) [trixie] - perl 5.40.1-6+deb13u1 https://lists.security.metacpan.org/cve-announce/msg/41020451/ Fixed by: https://github.com/Perl/perl5/commit/de19a0b0ad1900fef976c5c1400bd8f11ec6c6cb (v5.43.11)