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6.9

Wasmtime may crash host when handling certain WebAssembly modules

CVE-2026-119141 · published 6 days ago
Summary

Versions of the Wasmtime runtime before 48.0.6 and 49.0.3 can be forced to stop working if a specially crafted WebAssembly program is run. The problem occurs because the runtime does not correctly reset an internal flag during memory resizing, which can trigger a crash in the host application. Updating Wasmtime to version 48.0.6 or later (or 49.0.3 or later) resolves the issue.

What to do
  • Update bytecodealliance wasmtime to version 48.0.6 or later.
Affected software
VendorProductAffected versions
bytecodealliance wasmtime < 48.0.6
Original advisory text
Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Host Panic via realloc
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.
References
Fix within
Internet-facing 14 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically
  • Gives an attacker partial control
Severity
6.9 Medium
Exploitation
<1% chance of attack within 30 days
Type
CWE-1265Unintended Reentrant Invocation of Non-reentrant Code Via Nested Calls
Timeline
Published29 Oct 2026
Updated4 Nov 2026
First seen29 Oct 2026
Sources
CVE-2026-119141 · NVD
CVE-2026-119141 · MITRE
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