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CVE-2026-34983

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

Published: Apr 9, 2026Updated: Apr 15, 2026 Sources: CVE List NVDCWE-416
NVD MITRE
5.0CVSSMEDIUM
EPSS Score
0.1%
Top 98.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 Vector Breakdown

AV:LAC:LPR:LUI:RS:UC:NI:NA:H
Exploitability
AV:LAttack Vector
Local
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-416

Affected Products

wasmtimebytecodealliance
LibraryLibrary
OSS Libraries / generic-library
bytecodeallianceoss-projectOSS Libraries

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2
github.com

Timeline

Published
Apr 9, 2026
Last Updated
Apr 15, 2026

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