CVE-2026-34983
Use-after-free bug after cloning `wasmtime::Linker`
5.0
MEDIUM
CVSS 3.1
EPSS 0.01%
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.
How to fix CVE-2026-34983
To remediate CVE-2026-34983, upgrade the affected package to a fixed version below.
- —upgrade to 43.0.1 or later
- —upgrade to 43.0.1 or later
- —no fix listed
- —no fix listed
Is CVE-2026-34983 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- >= 43.0.0, < 43.0.1
- >= 43.0.0, < 43.0.1
- from 0
- from 0, <= 43.0.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | MEDIUM5.0 | CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H |