Use-after-free in Wasmtime - CVE-2026-34983
Published: April 10, 2026
Vulnerability identifier: #VU125754
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:P/AC:L/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-34983
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Bytecode Alliance
Affected software:
Wasmtime
Wasmtime
Detailed vulnerability description
The vulnerability allows an attacker with physical access to cause a denial of service.
The vulnerability exists due to use-after-free in wasmtime::Linker when cloning a linker, dropping the original instance, and then using the cloned instance. An attacker with physical access can trigger the vulnerable sequence of host embedder API calls to cause a denial of service.
Guest Wasm programs cannot control this issue, and the wasmtime CLI is not affected.
How to mitigate CVE-2026-34983
Install security update from vendor's website.