CVE-2025-65026

Description

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.

CVSS v3.1 Score

6.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weakness Type (CWE)

CWE-94 CWE-94

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
esm	esm.sh	< 136

References

Advisories & Patches

https://github.com/esm-dev/esm.sh/commit/87d2f6497574bf4448641a5527a3ac2beba5fd6c https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp

Exploits

https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2025-65026? +

CVE-2025-65026 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-65026? +

CVE-2025-65026 affects products from esm, specifically: esm.sh. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-65026? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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