What’s Vulnerable › Vulnerabilities

CVE-2026-119332: Ladybird: FinalizationRegistry::cleanup() heap use-after-free via reentrant unregister()

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-30 · updated 2026-10-30
• Weakness: CWE-416

Description

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.

Affected products

• LadybirdBrowser Ladybird: before 209579c96473c75bd5eba9701fcadb841a045964

References

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

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