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.

We have discovered 28,172 live websites that are affected by CVE-2026-57432.

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Affected Software

Product	Perl
Category	Programming Languages
Vulnerable Domains	28,172 live websites (100% of Perl install base)
Vulnerable Versions	from 0 through 5.43.10
Vulnerable Versions Count	69 versions ( 100% of all versions)