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 4.0
- 5.9
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 - CVSS 3.1
- 6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 28% of CVEs (scores of 2026-10-26)
- CWE
- CWE-129
- Published
- Modified
- Record from
- the NVD, synced
Affected
- bytecodealliance:wasmtime
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-jxhv-7h78-9775 | crates.io | wasmtime | <24.0.7 | 24.0.7 |
| GHSA-jxhv-7h78-9775 | crates.io | wasmtime | >=25.0.0 <36.0.7 | 36.0.7 |
| GHSA-jxhv-7h78-9775 | crates.io | wasmtime | >=37.0.0 <42.0.2 | 42.0.2 |
| GHSA-jxhv-7h78-9775 | crates.io | wasmtime | >=43.0.0 <43.0.1 | 43.0.1 |
| RUSTSEC-2026-0092 | crates.io | wasmtime | >=0.0.0-0 <24.0.7 >=25.0.0 <36.0.7 >=37.0.0 <42.0.2 >=43.0.0 <43.0.1 | 24.0.7, 36.0.7, 42.0.2, 43.0.1 |