CVE-2026-93749 source-map-js through 1.2.1 Event Loop Denial of Service
Attackers can cause denial of service by supplying large offset values in source maps, blocking the event loop in applications using source-map-js.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93749?
CVE-2026-93749 is a high-severity denial of service vulnerability in 7rulnik source-map-js, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-1284
Which versions are affected by CVE-2026-93749?
2 open source packages ship an affected version, including source-map-js.
| Package | Affected | Fixed in |
|---|---|---|
source-map-js npm | From 1.0.0 | 1.2.2 |
source-map-js npm | From 1.0.0 | 1.2.2 |
How do I fix CVE-2026-93749?
Upgrade source-map-js to 1.2.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-93749 being exploited?
There is no known exploitation of CVE-2026-93749 in the wild and no public exploit code.
Sources
Also known as AZL-103442, AZL-103478, CLEANSTART-2026-AC91052, CLEANSTART-2026-ME02070, CLEANSTART-2026-VU21760, CLEANSTART-2026-XM40960 and 19 more.