Wasmtime

Wasmtime 47.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a memory misalignment flaw in VMContext layout that causes undefined behavior when modules contain an odd number of exception tags. A WebAssembly module with an odd tag count misaligns subsequent host fields in embedders with exceptions enabled, although no exploitation path is currently known.

Published: 2026-10-29T15:58:14.355Z
Updated: 2026-10-29T17:14:39.514Z

Wasmtime 42.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a stack overflow vulnerability that allows guests to crash the host through recursive type drops. Guests can define a long chain of recursive types so that removing the top-level type triggers unbounded recursive drops, exhausting the host stack.

Published: 2026-10-29T15:58:17.461Z
Updated: 2026-10-29T17:14:32.292Z

Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a denial of service vulnerability that allows malicious Wasm modules to panic the host because the may_leave flag is not cleared during realloc. Attackers can call into the host from realloc while lowering stream or future results, such as cancelling the active read or re-waiting a waitable-set, crashing the host.

Published: 2026-10-29T15:58:20.531Z
Updated: 2026-10-29T17:14:25.649Z

Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a denial of service vulnerability that allows guest code to trigger a host panic through out-of-bounds zero-length stream operations. Malicious guests can perform zero-length component model stream reads or writes with unvalidated addresses, causing Direct{Source,Destination}::remaining to panic and crash WASIp3 embedders.

Published: 2026-10-29T15:58:21.991Z
Updated: 2026-11-04T01:29:32.979Z

wasmtime-wasi in Wasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 re-appends a trailing slash to rename source paths, causing renameat on macOS and FreeBSD hosts to follow directory symlinks. A guest with sandbox write access can rename a relative symlink such as "up/" to move host directories into its sandbox and read or write them.

Published: 2026-10-28T18:59:56.965Z
Updated: 2026-11-04T15:08:13.222Z