CVE-2026-34942

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocated strings. This meant that unaligned pointers could be passed to the host for transcoding which would trigger a host panic. This panic is possible to trigger from malicious guests which transfer very specific strings across components with specific addresses. Host panics are considered a DoS vector in Wasmtime as the panic conditions are controlled by the guest in this situation. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxhv-7h78-9775	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:bytecodealliance:wasmtime::::::rust::*
	cpe:2.3:a:bytecodealliance:wasmtime::::::rust::*
	cpe:2.3:a:bytecodealliance:wasmtime::::::rust::*
	cpe:2.3:a:bytecodealliance:wasmtime::::::rust::*

History

No history.

Information

Published : 2026-04-09 19:16

Updated : 2026-06-17 10:39

NVD link : CVE-2026-34942

Mitre link : CVE-2026-34942

CVE.ORG link : CVE-2026-34942

JSON object : View

Products Affected

bytecodealliance

wasmtime

CWE

CWE-129

Improper Validation of Array Index

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