Skip to content
CVE PROGRAM SOURCE RECORD5.9 Medium

CVE-2026-34942

Wasmtime panics when transcoding misaligned utf-16 strings

Description

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocated strings. This meant that unaligned pointers could be passed to the host for transcoding which would trigger a host panic. This panic is possible to trigger from malicious guests which transfer very specific strings across components with specific addresses. Host panics are considered a DoS vector in Wasmtime as the panic conditions are controlled by the guest in this situation. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

bytecodealliance wasmtime

  • < 24.0.7affected
  • >= 25.0.0, < 36.0.7affected
  • >= 37.0.0, < 42.0.2affected
  • >= 43.0.0, < 44.0.1affected

References