Low 1.0Published Apr 9, 2026

CVE-2026-34983Wasmtime has a use-after-free bug after cloning `wasmtime::Linker`

Updated under an hour ago (Oct 27, 2026, 9:50 AM ET)

Does this affect you?

It affects bytecodealliance wasmtime. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for bytecodealliance wasmtime

Exploited in the last 30 days

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: 1.0 LOW (v4.0, CNA)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
Weakness (CWE): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Apr 13, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

bytecodealliance wasmtime bytecodealliance:wasmtime (from the name)	from 43.0.0, < 43.0.1	CNA record
bytecodealliance wasmtime bytecodealliance:wasmtime	43.0.0	NVD

References

References

https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2	x-refsource-confirm, mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.