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PerlApplication

CVE-2026-8376

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-26
Fix available
A fix is available. Upgrade to after 5.43.10 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Perl versions through 5.43.10 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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Heap buffer overflow in Perl_study_chunk (regcomp_study.c) due to confusion between character and byte counts when calculating buffer size for quantified fixed substrings in regex compilation on 32-bit builds. The mincount * l calculation can overflow SSize_t, resulting in undersized SvGROW allocation and out-of-bounds write.

MitigationUpgrade Perl to a patched version beyond 5.43.10; avoid compiling untrusted regular expressions on 32-bit Perl builds; consider migrating to 64-bit Perl builds if possible.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
PerlApplication
Affected:<= 5.43.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Determine Perl architecture
    Run 'perl -V' and look for 'ptrsize' or use 'use Config; print $Config{ptrsize}' - a value of 4 indicates 32-bit, 8 indicates 64-bit
    Affected if Perl is compiled as a 32-bit binary (ptrsize equals 4)
  2. Check Perl version number
    Run 'perl -v' or 'perl -e "print $^V"' to obtain the version
    Affected if Version is 5.43.10 or lower (the vulnerability exists up to this version)
  3. Identify if processing regex compilation
    Review application code for calls to qr//, qr'' , m//, s///, or split with regex patterns that involve quantified fixed strings (for example: /(?:pattern){N}/ where N is large)
    Affected if The application compiles regex patterns, especially those containing quantified fixed strings with large minimum counts on 32-bit Perl

A system is affected if it runs a 32-bit Perl build version 5.43.10 or lower that compiles regex patterns with quantified fixed strings having large minimum counts.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 5.43.10
Vendor patch github.com →
Interim mitigation

Upgrade Perl to a patched version beyond 5.43.10; avoid compiling untrusted regular expressions on 32-bit Perl builds; consider migrating to 64-bit Perl builds if possible.

Recommended fix Moderate confidence
  1. Obtain the patch from the vendor commit: https://github.com/Perl/perl5/commit/5e7f119eb2bb1181be908701f22bf7068e722f1c.patch
  2. Review the patch to understand the fix applied to regcomp_study.c in the Perl_study_chunk function
  3. Apply the patch to the Perl source code
  4. Recompile Perl, ensuring the build targets the correct architecture (the vulnerability affects 32-bit builds)
  5. Test the patched Perl binary to verify the fix resolves the heap buffer overflow
  6. If compiling user-controlled regex patterns is part of your application, implement input validation to reject overly large quantifiers on fixed strings (e.g., patterns like /(?:A{1000000000})/) until the patch is applied

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Perl Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8376 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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