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9.9 Critical

CVE-2026-115889 Wasmtime is a runtime for WebAssembly

Description

Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values. The overflow can make Cranelift reference incorrect IR values, causing arbitrary miscompilation, type confusion, and other attacker-controlled effects that may escape the Wasm sandbox on any architecture using the default Cranelift backend. This issue is fixed in versions 36.0.19 and 43.0.0.

Affected products and versions

Product Affected versions Fixed in
wasmtime 37.0 37.0.0 → < 43.0.0 43.0.0
wasmtime 36.0 earliest → < 36.0.19 36.0.19

References

Timeline

  1. Published
  2. Last modified

Other CVEs of wasmtime

The 81 CVEs of wasmtime →
CVE-2026-121441 Wasmtime before 36.0.19, 37.0.0 before 48.0.7, and 49.0.0 before 49.0.4 contains a request smuggling vulnerability in… 6.3 Medium CVE-2026-121440 Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the… 6.3 Medium CVE-2026-121439 Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 contains a response splitting vulnerability in wasi-http p3… 6.9 Medium CVE-2026-119143 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic via Zero-Length Stream Writes 5.9 Medium
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