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CVE-2026-34944GHSA-QQFJ-4VCM-26HVRUSTSEC-2026-0087

Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 24.0.7, 36.0.7, 42.0.2, 44.0.1, 43.0.1
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, On x86-64 platforms with SSE3 disabled Wasmtime's compilation of the f64x2.splat WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but this data is not visible to WebAssembly guests. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • bytecodealliance wasmtime

    fixed in 24.0.7; From 25.0.0 · fixed in 36.0.7; From 37.0.0 · fixed in 42.0.2; From 43.0.0 · fixed in 44.0.1

  • wasmtimecrates.io

    fixed in 24.0.7

  • wasmtimecrates.io

    From 25.0.0 · fixed in 36.0.7

  • wasmtimecrates.io

    From 37.0.0 · fixed in 42.0.2

  • wasmtimecrates.io

    From 43.0.0 · fixed in 43.0.1

  • wasmtimecrates.io

    From 0.0.0-0 · fixed in 24.0.7; From 25.0.0 · fixed in 36.0.7; From 37.0.0 · fixed in 42.0.2; From 43.0.0 · fixed in 43.0.1

References 1

GitHub · bytecodealliance/wasmtime