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.
CVSS Score
8.4
EPSS Score
0.002
Published
2026-07-13
Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.10 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk.
When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie's match decision table is truncated with no warning or error.
A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.
CVSS Score
9.1
EPSS Score
0.004
Published
2026-07-13
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 a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds.
Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. For a quantified fixed substring with a large minimum count, the byte length mincount * l could overflow SSize_t, producing an undersized SvGROW allocation; the subsequent copy writes past the end of the buffer.
A caller that compiles an attacker-controlled regular expression on a 32-bit perl build triggers a heap buffer overflow at compile time.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-05-26
Perl versions from 5.9.4 before 5.40.4-RC1, from 5.41.0 before 5.42.2-RC1, from 5.43.0 before 5.43.9 contain a vulnerable version of Compress::Raw::Zlib.
Compress::Raw::Zlib is included in the Perl package as a dual-life core module, and is vulnerable to CVE-2026-3381 due to a vendored version of zlib which has several vulnerabilities, including CVE-2026-27171. The bundled Compress::Raw::Zlib was updated to version 2.221 in Perl blead commit c75ae9cc164205e1b6d6dbd57bd2c65c8593fe94.
CVSS Score
9.8
EPSS Score
0.007
Published
2026-03-29
A heap buffer overflow vulnerability was discovered in Perl.
Release branches 5.34, 5.36, 5.38 and 5.40 are affected, including development versions from 5.33.1 through 5.41.10.
When there are non-ASCII bytes in the left-hand-side of the `tr` operator, `S_do_trans_invmap` can overflow the destination pointer `d`.
$ perl -e '$_ = "\x{FF}" x 1000000; tr/\xFF/\x{100}/;'
Segmentation fault (core dumped)
It is believed that this vulnerability can enable Denial of Service and possibly Code Execution attacks on platforms that lack sufficient defenses.
CVSS Score
8.4
EPSS Score
0.005
Published
2025-04-13
A vulnerability was found in perl 5.30.0 through 5.38.0. This issue occurs when a crafted regular expression is compiled by perl, which can allow an attacker controlled byte buffer overflow in a heap allocated buffer.
CVSS Score
7.0
EPSS Score
0.008
Published
2023-12-18
CPAN.pm before 2.35 does not verify TLS certificates when downloading distributions over HTTPS.
CVSS Score
8.1
EPSS Score
0.015
Published
2023-04-29
HTTP::Tiny before 0.083, a Perl core module since 5.13.9 and available standalone on CPAN, has an insecure default TLS configuration where users must opt in to verify certificates.
CVSS Score
8.1
EPSS Score
0.017
Published
2023-04-29
Buffer overflow in the DBD::mysql module before 4.037 for Perl allows context-dependent attackers to cause a denial of service (crash) via vectors related to an error message.
CVSS Score
7.5
EPSS Score
0.041
Published
2016-10-05
The Crypt::DSA (aka Crypt-DSA) module 1.17 and earlier for Perl, when /dev/random is absent, uses the Data::Random module, which makes it easier for remote attackers to spoof a signature, or determine the signing key of a signed message, via a brute-force attack.
CVSS Score
5.8
EPSS Score
0.02
Published
2011-10-10
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