What’s Vulnerable › Vulnerabilities

CVE-2026-4176: 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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-29 · updated 2026-06-17
• Weakness: CWE-1395

Description

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.

Affected products

• perl: from 5.9.4 before 5.40.4; from 5.41.0 before 5.42.2; from 5.43.0 before 5.43.9 — fixed in 5.40.4, 5.42.2, 5.43.9

How to fix

Upgrade to a fixed version: perl 5.40.4, 5.42.2, 5.43.9. Check the vendor advisory for mitigations.

References

• https://github.com/Perl/perl5/commit/c75ae9cc164205e1b6d6dbd57bd2c65c8593fe94
• https://lists.security.metacpan.org/cve-announce/msg/37638919/
• https://metacpan.org/release/PMQS/Compress-Raw-Zlib-2.221/source/Changes
• https://metacpan.org/release/SHAY/perl-5.40.4/changes
• https://metacpan.org/release/SHAY/perl-5.42.2/changes
• https://www.cve.org/CVERecord?id=CVE-2026-3381
• http://www.openwall.com/lists/oss-security/2026/03/30/2

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