RCE in Esm Esm.sh
CVE-2025-65026
esm.sh is a nobuild content delivery network(CDN) for modern web development. Prior to version 136, The esm.sh CDN service contains a Template Literal Injection vulnerability (CWE-94) in its CSS-to-JavaScript module conversion feature. When a CSS file is requested with the ?module query parameter, esm.sh converts it to a JavaScript module by embedding the CSS content directly into a template literal without proper sanitization. An attacker can inject malicious JavaScript code using ${...} expressions within CSS files, which will execute when the module is imported by victim applications. This enables Cross-Site Scripting (XSS) in browsers and Remote Code Execution (RCE) in Electron applications. This issue has been patched in version 136.
Vulnerability class: RCE (Remote Code Execution)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.005 (38.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Esm Esm.sh
- Esm-Dev Esm.sh — versions < 136
Weakness classification (CWE)
References
- github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp (Exploit, Vendor Advisory)
- github.com/esm-dev/esm.sh/commit/87d2f6497574bf4448641a5527a3ac2beba5fd6c (Patch)
Frequently asked questions
- What is CVE-2025-65026?
- CVE-2025-65026 is a medium-severity vulnerability in Esm Esm.sh, classified under Code Injection. CVSS score: 6.1/10. Published 2025-11-19.
- How severe is CVE-2025-65026?
- Medium severity. CVSS v3 base score is 6.1 out of 10.