Wasmtime leaks host data with 64-bit tables and Winch (bytecodealliance wasmtime)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.32 % · percentile 25 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.
Weaknesses (CWE)
- CWE-681 — Incorrect Conversion between Numeric Types
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | LOW 2.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N | GitHub_M |
| CVSS 4.0 | LOW 2.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/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 | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N | NVD · nvd@nist.gov (Primary) |
European references
- ENISA EUVD · EUVD-2026-21024
- GCVE · GCVE-0-2026-34945
Affected configurations (NVD CPE)
cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*≥ 25.0.0 < 36.0.7cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*≥ 37.0.0 < 42.0.2cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*≥ 43.0.0 < 43.0.1
Affected products
| Product | Versions |
|---|---|
| bytecodealliance · wasmtime | affected >= 25.0.0, < 36.0.7 ; affected >= 37.0.0, < 42.0.2 ; affected >= 43.0.0, < 44.0.1 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |