CVE-2026-56018 Denial of service in JavaScript::Minifier::XS
A memory leak in the JavaScript::Minifier::XS Perl library allows attackers to cause denial of service via unbounded memory growth during repeated minification calls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-56018?
CVE-2026-56018 is a high-severity denial of service vulnerability in GTERMARS JavaScript::Minifier::XS, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
JavaScript::Minifier::XS versions before 0.16 for Perl leak memory on every call to minify(), allowing unbounded memory growth.
In JsMinify (XS.xs) the cleanup frees only the NodeSet structures and never the per-token contents buffers allocated in JsSetNodeContents; JsDiscardNode unlinks nodes without freeing their contents. Each token's contents buffer is therefore leaked on every call, and the two early returns taken when the node list is empty leak the whole NodeSet.
A long-lived process that minifies repeatedly, such as an asset pipeline or a server-side minifier endpoint, grows in memory without bound until it exhausts available memory and is killed, causing denial of service.
Which versions are affected by CVE-2026-56018?
How do I fix CVE-2026-56018?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-56018 being exploited?
There is no known exploitation of CVE-2026-56018 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-56018, DEBIAN-CVE-2026-56018, GHSA-fvxv-8c37-qrc6, UBUNTU-CVE-2026-56018.