CVE-2026-16634
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 · uneditedTOML::XS versions before 0.06 for Perl bundle an unsupported and vulnerable version of tomlc99. The tomlc99 library is no longer maintained, and has an uncontrolled recursion vulnerability publicly reported in the issue tracker. Any caller that passes untrusted TOML to from_toml risks a stack overflow from a deeply-nested document. TOML::XS version 0.06 or later uses the successor tomlc17 library.
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 confidenceTOML::XS Perl module before version 0.06 bundles the unmaintained tomlc99 C library which contains an uncontrolled recursion vulnerability. When the from_toml function processes a deeply-nested TOML document, it triggers excessive recursive calls leading to stack overflow and denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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 checksWork through these to decide whether this CVE applies to you.
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Verify TOML::XS is installedRun: perl -MTOML::XS -e 'print TOML::XS->VERSION'Affected if The module is not installed or the command fails, meaning TOML::XS is not in use.
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Check installed version against vulnerabilityCompare the version output from step 1 to 0.06. Versions before 0.06 are vulnerable.Affected if The installed version is lower than 0.06.
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Identify TOML parsing usageSearch codebase for 'use TOML::XS', 'from_toml', or 'TOML::XS->new' to see if TOML::XS is actually being called.Affected if No code paths invoke TOML::XS functions, the vulnerability is not reachable.
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Check for nested TOML input handlingAudit any TOML input sources: if user-controlled TOML is parsed with from_toml, deep nesting could trigger the overflow.Affected if The application parses untrusted TOML with depth not controlled by the developer.
You are affected if TOML::XS version lower than 0.06 is installed AND your code uses from_toml to parse TOML documents that could contain deeply nested structures.
Generated from the published advisory. Verify against your own configuration.
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 · scopedUpgrade TOML::XS to version 0.06 or later which replaces the vulnerable tomlc99 with the maintained tomlc17 library. If immediate upgrade is not feasible, do not pass untrusted TOML input to from_toml.
TOML::XS version 0.06 or later (which uses the tomlc17 library instead of the vulnerable tomlc99)
- Check the currently installed version of TOML::XS: perl -MTOML::XS -e 'print $TOML::XS::VERSION'
- Upgrade TOML::XS to version 0.06 or later using your Perl module manager (e.g., cpanm TOML::XS or cpan TOML::XS)
- Verify the upgraded version is 0.06 or later: perl -MTOML::XS -e 'print $TOML::XS::VERSION'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-16634 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-16634 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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