High advisory for Ladybird

Advisory overview

Ladybird is a truly independent web browser. Prior to 209579c96473c75bd5eba9701fcadb841a045964, FinalizationRegistry::cleanup() in Libraries/LibJS/Runtime/FinalizationRegistry.cpp removed a dead record from m_records, retained an iterator to the next FinalizationRecord, and then invoked attacker-controlled JavaScript through the cleanup callback. If that callback called unregister() for the next record, remove_by_token() freed the node referenced by the retained iterator, and the next cleanup iteration read its target and held_value fields after free. This reliably crashes instrumented WebContent builds and creates a memory-corruption primitive in production builds. This vulnerability is fixed by commit 209579c96473c75bd5eba9701fcadb841a045964.

Related references

• https://github.com/LadybirdBrowser/ladybird/commit/209579c96473c75bd5eba9701fcadb841a045964
• https://github.com/LadybirdBrowser/ladybird/security/advisories/GHSA-6cmv-xmff-qjph