Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The npm package source-map-js, versions from 1.0.0 before 1.2.2, does not validate the line offset value for each section of an indexed source map. An attacker who can get the application to process a crafted indexed source map can supply very large offset values that block the Node.js event loop for long periods, so the service cannot handle other requests. The fix is to upgrade source-map-js to version 1.2.2 or later.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 8.7 | High | 4.0 | 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 | CNA (VulnCheck) |
- CISA KEV Not listed.
- EPSS 0.0046, the 39th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 13:34 UTC First seen by agentprime
- 31 Oct 2026, 13:34 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-68fv-2mgg-jv7q
- OSV: GHSA-68fv-2mgg-jv7q
- nvd.nist.gov/vuln/detail/CVE-2026-93749
- github.com/7rulnik/source-map-js/issues/76
- github.com/7rulnik/source-map-js/pull/79
- github.com/7rulnik/source-map-js/commit/cf7658058ceeaa8619d5ae0ec90be6905209d016
- github.com/7rulnik/source-map-js
- github.com/7rulnik/source-map-js/blob/c1cd8904bb7bd0c7fb5879fcda48134d82a27934/lib/source-node.js#L115-L118
- github.com/7rulnik/source-map-js/releases/tag/v1.2.2
- www.vulncheck.com/advisories/source-map-js-through-1.2.1-event-loop-denial-of-service