CVE-2026-57432

Perl versions through 5.43.10 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack. S_measure_struct adds each item's size times its repeat count to a running total with no overflow check, so a large repeat count in a pack or unpack template wraps the signed SSize_t total negative. The @, X, and x position codes then guard their moves with a signed length comparison that passes when the length is negative, advancing the buffer pointer out of bounds. A template derived from untrusted input can read heap memory past the buffer and return it to the caller.

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• perl 5.40.1-8 (bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1138905; bug #1142036) https://lists.security.metacpan.org/cve-announce/msg/41780102/ Fixed by: https://github.com/Perl/perl5/commit/5f7eb6bbbe0510964e3fb1d6bb691e5445913e55 (v5.43.11) Fixed by: https://github.com/Perl/perl5/commit/40754edc72dd3e513d758153c0e2f0215897740e (v5.43.11)