CVE-2026-53486: Decompress: Archive extraction can create files and links outside of the target directory

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.7%, percentile 54: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 54% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes @xhmikosr/decompress (npm) < 10.2.1, fixed in 10.2.1; @xhmikosr/decompress (npm) >= 11.0.0, < 11.1.3, fixed in 11.1.3; decompress (npm) <= 4.2.1, no fixed version listed. Check your lockfile, including transitive dependencies.

What it is

The decompress package for Node.js extracts archives. Prior to 10.2.1 and 11.1.3, archive extraction can create files and links outside the target directory. When extracting an archive to a directory, a crafted archive can read or write files outside that directory because hardlink and symlink entries are created without checking where targets point, path containment used a string prefix comparison, and file modes failed to remove setuid, setgid, or sticky bits. This issue is fixed in @xhmikosr/decompress versions 10.2.1 and 11.1.3.

From the GitHub advisory

Impact

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.

Weakness type: CWE-22, CWE-59, CWE-732.

Product: @xhmikosr/decompress (npm) · Assigned by: GitHub_M · Published: 2026-07-14

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.75% probability of exploitation activity in the next 30 days; percentile 54.

Timeline

• 2026-07-06 — GitHub-reviewed advisory GHSA-mp2f-45pm-3cg9 published (critical)
• 2026-07-14 — CVE record published by GitHub_M
• 2026-07-15 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-mp2f-45pm-3cg9 github.com
2. CVE.org record CVE-2026-53486 cve.org
3. NVD entry CVE-2026-53486 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
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7. github.com github.com
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10. github.com github.com

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