CVE-2026-34983
In 43.0.0, cloning a wasmtime::Linker is unsound and can result in use-after-free bugs.
Does this matter?
Lower severity and a low EPSS score (0.12%). Track it; it rarely justifies an emergency change on its own.
Description
Wasmtime is a runtime for WebAssembly. In 43.0.0, cloning a wasmtime::Linker is unsound and can result in use-after-free bugs. This bug is not controllable by guest Wasm programs. It can only be triggered by a specific sequence of embedder API calls made by the host. Specifically, the following steps must occur to trigger the bug clone a wasmtime::Linker, drop the original linker instance, use the new, cloned linker instance, resulting in a use-after-free. This vulnerability is fixed in 43.0.1.
- CVSS 4.0
- 1.0 LOWCVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.12% probability · 2th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- bytecodealliance/wasmtime
- Source
- security-advisories@github.com
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2Mitigation, Vendor Advisory
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2Mitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.