CVE-2026-23644

esm.sh has path traversal in `extractPackageTarball` that enables file writes from malicious packages

HIGH
7.5
CVSS Score
Published: January 18, 2026 at 10:49 PM UTC
Updated: June 17, 2026 at 10:21 AM UTC
2 products affected across 2 vendorsEsm.shEsm.sh

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Severity
HIGH7.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 136
v < 0.0.0-20260116051925-c62ab83c589e
Affected range stops below 0.0.0-20260116051925-c62ab83c589e, so it looks safe — our inference, not a vendor statement

References (4)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/esm-dev/esm.sh/security/advisories/GHSA-2657-3c98-63jq
x_refsource_MISCExploitVendor Advisory
Source: cverecord
https://pkg.go.dev/vuln/GO-2025-4138

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-22

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