CVE-2026-35195

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 between components contains a bug where the return value of a guest component's realloc is not validated before the host attempts to write through the pointer. This enables a guest to cause the host to write arbitrary transcoded string bytes to an arbitrary location up to 4GiB away from the base of linear memory. These writes on the host could hit unmapped memory or could corrupt host data structures depending on Wasmtime's configuration. Wasmtime by default reserves 4GiB of virtual memory for a guest's linear memory meaning that this bug will by default on hosts cause the host to hit unmapped memory and abort the process due to an unhandled fault. Wasmtime can be configured, however, to reserve less memory for a guest and to remove all guard pages, so some configurations of Wasmtime may lead to corruption of data outside of a guest's linear memory, such as host data structures or other guests's linear memories. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.
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:43.0.0:*:*:*:*:rust:*:*

History

15 Apr 2026, 13:00

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 5.4
CPE cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*
cpe:2.3:a:bytecodealliance:wasmtime:43.0.0:*:*:*:*:rust:*:*
First Time Bytecodealliance
Bytecodealliance wasmtime
References () https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm - () https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm - Vendor Advisory

09 Apr 2026, 19:16

Type Values Removed Values Added
New CVE

Information

Published : 2026-04-09 19:16

Updated : 2026-04-15 13:00


NVD link : CVE-2026-35195

Mitre link : CVE-2026-35195

CVE.ORG link : CVE-2026-35195


JSON object : View

Products Affected

bytecodealliance

  • wasmtime
CWE
CWE-787

Out-of-bounds Write