CVE-2023-27477
wasmtime is a fast and secure runtime for WebAssembly.
Does this matter?
Lower severity and a low EPSS score (0.62%). Track it; it rarely justifies an emergency change on its own.
Description
wasmtime is a fast and secure runtime for WebAssembly. Wasmtime's code generation backend, Cranelift, has a bug on x86_64 platforms for the WebAssembly `i8x16.select` instruction which will produce the wrong results when the same operand is provided to the instruction and some of the selected indices are greater than 16. There is an off-by-one error in the calculation of the mask to the `pshufb` instruction which causes incorrect results to be returned if lanes are selected from the second vector. This codegen bug has been fixed in Wasmtiem 6.0.1, 5.0.1, and 4.0.1. Users are recommended to upgrade to these updated versions. If upgrading is not an option for you at this time, you can avoid this miscompilation by disabling the Wasm simd proposal. Additionally the bug is only present on x86_64 hosts. Other platforms such as AArch64 and s390x are not affected.
- CVSS 3.1
- 4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
- EPSS
- 0.62% probability · 48th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-193
- Affected
- bytecodealliance/cranelift-codegen · bytecodealliance/wasmtime
- Source
- security-advisories@github.com
EPSS 0.6% since 4 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.wasm_simdProduct
- https://github.com/bytecodealliance/wasmtime/commit/5dc2bbccbb363e474d2c9a1b8e38a89a43bbd5d1Patch
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-xm67-587q-r2vwMitigation, Patch, Vendor Advisory
- https://github.com/webassembly/simdNot Applicable
- https://groups.google.com/a/bytecodealliance.org/g/sec-announce/c/Mov-ItrNJsQMailing List, Release Notes, Vendor Advisory
- https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.wasm_simdProduct
- https://github.com/bytecodealliance/wasmtime/commit/5dc2bbccbb363e474d2c9a1b8e38a89a43bbd5d1Patch
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-xm67-587q-r2vwMitigation, Patch, Vendor Advisory
- https://github.com/webassembly/simdNot Applicable
- https://groups.google.com/a/bytecodealliance.org/g/sec-announce/c/Mov-ItrNJsQMailing List, Release Notes, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.