CVE-2026-124683 | BDVDB-2026-402446 Detail

Description#

Eclipse Langium versions 3.2.0 through 4.4.0 contain an inefficient algorithmic complexity issue (CWE-407) in the opt-in IndentationAwareTokenBuilder and IndentationAwareLexer. When producing DEDENT tokens, the token builder recomputes line numbers by re-scanning the entire preceding document text. A document whose indentation changes on most lines then takes quadratic time to tokenize. Because tokenization is synchronous, a crafted document of a few hundred kilobytes can block the Node.js event loop for tens of seconds. That causes a DoS for every user served by the same process. Languages built with the DefaultLexer and DefaultTokenBuilder are unaffected.

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Exploit#

History#

1. Version 12026-11-09Record published in the CVE List.