What’s Vulnerable › Vulnerabilities

CVE-2026-93749: source-map-js through 1.2.1 Event Loop Denial of Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-18 · updated 2026-09-22
• Weakness: CWE-1284

Description

source-map-js through 1.2.1 fails to validate the per-section offset line value in indexed source maps, allowing attackers to specify arbitrary numeric values. Attackers can supply extremely large offset line values that cause synchronous event loop blocking for extended periods, preventing the service from handling other requests.

Affected products

• Npm Source-Map-Js: from 1.0.0 before 1.2.2 — fixed in 1.2.2
• 7rulnik source-map-js: through 1.2.1

How to fix

Upgrade to a fixed version: Npm Source-Map-Js 1.2.2. Check the vendor advisory for mitigations.

References

• https://github.com/7rulnik/source-map-js
• https://github.com/7rulnik/source-map-js/blob/c1cd8904bb7bd0c7fb5879fcda48134d82a27934/lib/source-node.js#L115-L118
• https://github.com/7rulnik/source-map-js/issues/76
• https://www.vulncheck.com/advisories/source-map-js-through-1.2.1-event-loop-denial-of-service

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