CVE-2026-34983

1.0 LOW 0.1% exploit odds Fix listed Memory safety

What it is

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.

At a glance

Exploitability: Can be exploited with physical access with an admin-level account, but needs a user to act. Limited direct impact.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-04-09 19:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-26 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 1.0 LOW (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-04-09 19:16 UTC
Last modified: 2026-10-26 21:10 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-416 · Use after free
Record status: Analyzed

Affected

Bytecodealliance Wasmtime 43.0.0

Attack profile CVSS 4.0 · 1.0

Attack vector: Physical
Complexity: High
Attack requirements: Present
Privileges needed: High
User interaction: Active
Confidentiality: Low
Integrity: Low
Availability: Low

Raw vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-34983.md and follow it. Check whether this project is affected by CVE-2026-34983. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record