CVE-2026-53486

Decompress: Archive extraction can create files and links outside of the target directory

When extracting an archive to a directory, a crafted archive can read or write files outside that directory. The flaw is in the code that writes the parsed entries, so it affects every format decompress handles: tar, tar.gz, tar.bz2, and zip by default, plus any others added through the plugins option.

A link (hardlink) or symlink entry is created without checking where its target points. A hardlink can be aimed at any file the running process can read; that file then appears inside the output directory and its contents are exposed. A symlink can point outside the output directory and redirect a later write.

The path containment check used a string prefix comparison (realPath.indexOf(outputPath) !== 0). Output /srv/out does not contain /srv/out-old, but the prefix comparison treats it as inside, so an entry can escape into a sibling directory whose name starts with the output directory name.

File modes were applied as mode & ~umask, which does not remove the setuid, setgid, or sticky bits. A crafted entry can create a setuid or setgid file. This matters when extraction runs as root, for example in CI, containers, or install scripts.

Any code that extracts archives from an untrusted or attacker-influenced source is affected. Archives are commonly downloaded before extraction, so this is reachable over the network in many setups.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-53486 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (10.2.1, 11.1.3); upgrading removes the vulnerable code path.

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Fixed in @xhmikosr/decompress 10.2.1 and 11.1.3. Link targets are now resolved and checked against the output directory, containment uses path.relative, and setuid, setgid, and sticky bits are removed.

The upstream decompress package is unmaintained, and all versions through its last release (4.2.1) have the same flaws. There is no upstream fix. Migrate to @xhmikosr/decompress 11.1.3 or later.

1. What is CVE-2026-53486? CVE-2026-53486 is a critical-severity path traversal vulnerability in @xhmikosr/decompress (npm), affecting versions < 10.2.1. It is fixed in 10.2.1, 11.1.3. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-53486? CVE-2026-53486 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-53486?
   • @xhmikosr/decompress (npm) (versions < 10.2.1)
   • decompress (npm) (versions <= 4.2.1)
4. Is there a fix for CVE-2026-53486? Yes. CVE-2026-53486 is fixed in 10.2.1, 11.1.3. Upgrade to this version or later.
5. Is CVE-2026-53486 exploitable, and should I be worried? Whether CVE-2026-53486 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-53486 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-53486?
   • Upgrade @xhmikosr/decompress to 10.2.1 or later
   • Upgrade @xhmikosr/decompress to 11.1.3 or later