Quick answers
- Is CVE-2026-124683 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-124683 being exploited in the wild.
- How severe is CVE-2026-124683?
- Informational severity, published 9 November 2026.
- Which products and versions are affected?
- Eclipse Langium 3.2.0 through 4.4.0.
- Is there a fix for CVE-2026-124683?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-124683 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-124683?
- Check whether you run Eclipse Langium at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The IndentationAwareTokenBuilder and IndentationAwareLexer components recompute line numbers inefficiently by re-scanning the entire preceding document text for each DEDENT token, resulting in O(n²) complexity. A document with indentation changes on most lines triggers quadratic tokenization time. The synchronous tokenization blocks the Node.js event loop, enabling denial of service; only opt-in configurations are affected, as the default tokenizer is unaffected.
Affected products
- Eclipse Langium 3.2.0 through 4.4.0
Timeline
- 2026-11-09: disclosed