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
Stig Palmquist 13 Jul 2026 15:45 UTC
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CVE-2026-57432 CPAN Security Group
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CVE ID: CVE-2026-57432
Distribution: perl
Versions: through 5.43.10
MetaCPAN: https://metacpan.org/dist/perl
VCS Repo: https://github.com/Perl/perl5
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
Description
-----------
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.
Problem types
-------------
- CWE-190 Integer Overflow or Wraparound
- CWE-125 Out-of-bounds Read
Solutions
---------
Apply the upstream patches. The fix is included in the Perl 5.43.11
development release.
References
----------
https://github.com/Perl/perl5/commit/5f7eb6bbbe0510964e3fb1d6bb691e5445913e55.patch
https://github.com/Perl/perl5/commit/40754edc72dd3e513d758153c0e2f0215897740e.patch