CVE-2026-56017
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…
Description
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-56017 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-56017 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-56017. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-56017 in your dependencies?
O3 detects CVE-2026-56017 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.