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Out-of-bounds ReadWeakness · CWE-125

CVE-2026-56017

HIGH · 7.5 CVSS v3.1 Published 2026-06-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click 7 weeks old

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
JavaScript::Minifier::XS versions before 0.16 for Perl crash with a NULL pointer dereference when the first meaningful token of the input is a slash. The regexp versus division disambiguator in JsTokenizeString (XS.xs) inspects the previous token's last byte to choose between a regexp literal and a division operator. When a slash is the first meaningful token, with the start of input or only whitespace and comments before it, there is no valid preceding token: the walk back over whitespace and comment nodes runs off the head of the node list to NULL, and the byte lookup reads through a NULL contents pointer at an underflowed length index. The following identifier check dereferences the same NULL pointer. The crash is reachable through the public minify() API, so input as small as a single slash byte crashes the calling process. A service that minifies untrusted or third-party JavaScript can be crashed by a remote request, causing denial of service.

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

JavaScript::Minifier::XS before 0.16 contains a NULL pointer dereference in the regexp versus division disambiguator in JsTokenizeString (XS.xs). When a slash is the first meaningful token (at start of input or after only whitespace/comments), the code attempts to read the previous token's last byte but walks off the node list to NULL, then reads through this NULL pointer at an underflowed index and dereferences it again during identifier check. This is reachable via the public minify() API with input as small as a single slash byte.

MitigationUpgrade to JavaScript::Minifier::XS version 0.16 or later. Until upgraded, do not process untrusted or third-party JavaScript input with this module as it will cause immediate process crash 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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Check installed version of JavaScript::Minifier::XS
    Run `perl -MJavaScript::Minifier::XS -e 'print $JavaScript::Minifier::XS::VERSION'` or check via cpan/cpanm listing
    Affected if version is empty or the command fails (module not installed)
  2. Verify the exact version number
    If installed, compare the reported version to 0.16 using version parsing: `perl -Mversion -e 'print version->parse($ARGV[0]) cmp version->parse("0.16")' <version>`
    Affected if version returns value less than 0.16 (e.g., 0.15, 0.14, etc.)
  3. Inspect code using this module
    Search source files for 'use JavaScript::Minifier::XS' or 'minify_js' function calls to see if the module is in use
    Affected if module is loaded and minify() is called on untrusted input
  4. Check for single-slash test cases
    Audit test or input handling code that may pass arbitrary JavaScript to minify(), look for patterns that could pass a lone '/' character
    Affected if code processes JavaScript input without sanitization that could include a standalone slash

If JavaScript::Minifier::XS version is below 0.16 and the minify() function is being used to process any JavaScript input (including input that could be or become a single slash), the environment is affected by this NULL pointer dereference vulnerability.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to JavaScript::Minifier::XS version 0.16 or later. Until upgraded, do not process untrusted or third-party JavaScript input with this module as it will cause immediate process crash and denial of service.

Recommended fix Moderate confidence

JavaScript::Minifier::XS version 0.16

  1. Install the latest version of JavaScript::Minifier::XS from CPAN (version 0.16 or later) using 'cpan JavaScript::Minifier::XS' or 'cpanm JavaScript::Minifier::XS'
  2. Verify the installed version by running 'perl -MJavaScript::Minifier::XS -e 'print $JavaScript::Minifier::XS::VERSION'
  3. If using this module in a service that processes untrusted JavaScript, ensure the service is restarted after the upgrade

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2026-56017 in production — separate from our analysis above.

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