{"id":"RUSTSEC-2026-0402","aliases":[],"status":"published","title":"Heap buffer overflow in `CCtx::try_clone` on a multithreaded context","description":"`CCtx::try_clone` (`experimental` feature, deprecated) copies tables sized\nfrom the context's applied parameters. Starting a multithreaded frame\n(`zstdmt` feature) replaces those parameters with the workers' without\nresizing the context's own tables, so after an abandoned single-threaded\nframe, the copy wrote up to 512 KiB past a heap allocation, or read past\none. This became reachable with the bundled zstd 1.5.6.\n\nThe flaw was corrected by refusing `try_clone` (and the unsafe\n`compress_block`) once `NbWorkers` was set on the context.","facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"published":"2026-10-16T12:00:00Z","modified":"2026-11-02T09:30:04Z","fixes":[{"ecosystem":"crates.io","package":"zstd-safe","fixed_in":["7.4.0","8.2.0"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"crates.io","package":"zstd-safe","ranges":[{"type":"SEMVER","events":[{"introduced":"4.1.4"},{"fixed":"7.4.0"},{"introduced":"8.0.0-0"},{"fixed":"8.2.0"}]}]}],"references":[{"url":"https://crates.io/crates/zstd-safe","tags":["package"]},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0402.html","tags":["advisory"]},{"url":"https://github.com/gyscos/zstd-rs/commit/682b8b2967cf4aba5cfe2d940d1e381a3e23211a","tags":["web"]},{"url":"https://github.com/gyscos/zstd-rs/pull/384","tags":["web"]}],"sources":{"osv":[{"id":"RUSTSEC-2026-0402","title":"Heap buffer overflow in `CCtx::try_clone` on a multithreaded context","description":"`CCtx::try_clone` (`experimental` feature, deprecated) copies tables sized\nfrom the context's applied parameters. Starting a multithreaded frame\n(`zstdmt` feature) replaces those parameters with the workers' without\nresizing the context's own tables, so after an abandoned single-threaded\nframe, the copy wrote up to 512 KiB past a heap allocation, or read past\none. This became reachable with the bundled zstd 1.5.6.\n\nThe flaw was corrected by refusing `try_clone` (and the unsafe\n`compress_block`) once `NbWorkers` was set on the context.","status":"published","published":"2026-10-16T12:00:00Z","modified":"2026-11-02T09:30:04.162155944Z","updated_at":"2026-11-02T15:53:40.430679Z"}]}}