CVE-2026-4176
CRITICAL: Perl core Compress::Raw::Zlib vulnerable; potential RCE via crafted input.
Is CVE-2026-4176 being exploited?
Not confirmed. CVE-2026-4176 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.73% probability of exploitation in the next 30 days.
How severe is CVE-2026-4176?
CVE-2026-4176 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-4176?
Yes. A fix has been recorded for CVE-2026-4176. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-4176 affect?
CVE-2026-4176 affects Perl 5.9.4 - 5.40.3, Perl 5.41.0 - 5.42.1, Perl 5.43.0 - 5.43.8. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-4176?
Upgrade Perl to patched release with fixed zlib
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via decompression of crafted data in affected Perl versions.
Patch when possible
- affected>= 5.9.4 and < 5.40.4-RC1
- affected>= 5.41.0 and < 5.42.2-RC1
- affected>= 5.43.0 and < 5.43.9
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.