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CVE-2026-23644VulnerabilityPublished Updated

CVE-2026-23644: esm.sh · Path Traversal

Affects esm.shSource CVE Database V5

0

Not known to be exploited · CVSS 7.7 High : upgrade to 0.0.0-20260116051925-c62ab83c589e soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score
7.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.0.0-20260116051925-c62ab83c589e
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

What to do

Upgrade esm.sh to 0.0.0-20260116051925-c62ab83c589e.

Affected software

ProductAffectedFixed in
esm-devesm.shAffected
  • <0.0.0-20260116051925-c62ab83c589e
Fixed in
  • 0.0.0-20260116051925-c62ab83c589e
Gogithub.com/esm-dev/esm.shpkg:golang/github.com/esm-dev/esm.shOther threatsAffected–Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately upgrade esm.sh to version 0.0.0-20260116051925-c62ab83c589e or later, which contains the fix for this path traversal vulnerability. Beyond upgrading, organizations should audit all tar file handling processes to ensure that path validation does not solely rely on path.Clean but includes checks to reject absolute paths and path traversal sequences (e.g., '../'). Implement sandboxing or containerization for esm.sh services to limit filesystem access in case of exploitation. Employ file integrity monitoring on directories used by esm.sh to detect unauthorized file modifications. Incorporate security scanning in CI/CD pipelines to detect vulnerable esm.sh versions and malicious tar files. Network-level protections such as web application firewalls (WAFs) can be tuned to detect suspicious requests related to tar file uploads or esm.sh interactions. Finally, monitor logs and alerts for unusual file system activity or errors indicating exploitation attempts. Coordinated vulnerability disclosure and information sharing within European cybersecurity communities can aid in early detection of exploitation attempts.

Description

esm.sh is a no-build content delivery network (CDN) for web development. Prior to Go pseeudoversion 0.0.0-20260116051925-c62ab83c589e, the software has a path traversal vulnerability due to an incomplete fix. `path.Clean` normalizes a path but does not prevent absolute paths in a malicious tar file. Commit https://github.com/esm-dev/esm.sh/commit/9d77b88c320733ff6689d938d85d246a3af9af16, corresponding to pseudoversion 0.0.0-20260116051925-c62ab83c589e, fixes this issue.

References

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