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Vulnerabilities

Vulnerability · CVE-2026-44593

esm.sh is a no-build content delivery network (CDN) for web development.

Published May 28, 2026 · catalog updated Jun 17, 2026 · esm.sh is a no-build

Check if you run it

No confirmed exploitation is on record for CVE-2026-44593. EPSS is 0.50%. Act only if a listed version of esm.sh is a no-build is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (esm.sh is a no-build).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.50%
Remediation
Advisory link
Affected products
See sources for product scope

esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates the path components without sanitizing them, producing a storage key. When this key is used, the underlying file system resolves the relative segments and writes the file to the specified path. Thus an attacker can craft a request that writes data to arbitrary locations on the server.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-44593

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-44593. EPSS is 0.50%. Act only if a listed version of esm.sh is a no-build is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-22: Path Traversal. EPSS 0.50%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 28, 2026 · NIST NVD

    Detected

    esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates the path components without sanitizing them, producing a storage key. When this key is used, the underlying file system r

  2. Jun 17, 2026 · NIST NVD

    Updated

    esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates the path components without sanitizing them, producing a storage key. When this key is used, the underlying file system r

Sources

  • CVE.orgVulnerability recordCVE-2026-44593

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-44593

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-44593

    esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates t

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.