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9.9
CVE-2026-115893: Wasmtime on ARM can jump outside sandbox
CVE-2026-115893 · published 12 days ago
Summary
The Wasmtime WebAssembly engine on ARM (aarch64) systems could miscompile a large jump table instruction, causing the code to branch to an unexpected location. This could let a malicious WebAssembly module break out of its isolation and run arbitrary code. Update Wasmtime to version 36.0.19, 48.0.7, 49.0.4 or later to resolve the problem.
What to do
- Update wasmtime-publish wasmtime to version 49.0.4.
- Update wasmtime to version 49.0.4.
- Update wasmtime to version 36.0.19.
- Update wasmtime to version 48.0.7.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| crates.io | wasmtime-publish | wasmtime |
>= 49.0.0, < 49.0.4 Fix: upgrade to 49.0.4
|
| rust | – | wasmtime |
>= 49.0.0, < 49.0.4 < 36.0.19 >= 37.0.0, < 48.0.7 Fix: upgrade to 49.0.4
|
Original advisory text
Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction
Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on aarch64 can compile a Wasm br_table instruction with more than approximately 256,000 targets so that it has an incorrect conditional branch target. The branch can then jump to arbitrary other code at a user-controlled offset, allowing a user-controlled Wasm module to escape the sandbox on aarch64 engines using the default Cranelift backend. This issue is fixed in versions 36.0.19, 48.0.7, and 49.0.4.
References
- https://crates.io/crates/wasmtime Product
- https://github.com/bytecodealliance/wasmtime/pull/14826 Patch
- https://rustsec.org/advisories/RUSTSEC-2026-0379.html
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/115xxx/CVE-2026-1158... Vendor Advisory
- https://github.com/advisories/GHSA-mghf-wjfp-p5xm
- https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19 URL
- https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7 URL
- https://github.com/bytecodealliance/wasmtime/releases/tag/v49.0.4 URL
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-mghf-wjfp-... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-115893 Vendor Advisory
- https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937... Patch
- https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17... Patch
- https://github.com/bytecodealliance/wasmtime/commit/e61df1b454be9313d61a5f8de077... Patch
- https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8c... Patch
- https://github.com/bytecodealliance/wasmtime/pull/14818 Patch
- https://github.com/bytecodealliance/wasmtime/pull/14819 Patch
- https://github.com/bytecodealliance/wasmtime/pull/14820 Patch
Internet-facing
14 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit (estimated)
- Gives an attacker full control (estimated)
Type
CWE-691Insufficient Control Flow Management
Timeline
Published23 Oct 2026
Updated30 Oct 2026
First seen21 Oct 2026
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