What’s Vulnerable › Vulnerabilities

CVE-2026-57432: Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack

• Severity: high (CVSS 8.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-13 · updated 2026-10-24
• Weakness: CWE-125

Description

Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 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.

Affected products

• perl: through 5.43.10

References

• https://github.com/Perl/perl5/commit/40754edc72dd3e513d758153c0e2f0215897740e.patch
• https://github.com/Perl/perl5/commit/5f7eb6bbbe0510964e3fb1d6bb691e5445913e55.patch
• http://www.openwall.com/lists/oss-security/2026/07/13/6

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