EUVD-2026-20990
GHSA-jxhv-7h78-9775
CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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
Lifecycle Timeline
4Description
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.
Analysis
Wasmtime prior to versions 24.0.7, 36.0.7, 42.0.2, and 43.0.1 fails to properly validate pointer alignment when transcoding strings into UTF-16 or Latin-1+UTF-16 encodings within the Component Model, allowing authenticated malicious WebAssembly guests to trigger host panics by passing specially crafted unaligned pointers across component boundaries. This denial-of-service vulnerability requires authenticated access and specific string configurations but results in controllable host crashes. …
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