Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction
CVE-2026-115893
Summary When running with the Cranelift compiler backend on an aarch64 target, Wasmtime can compile a Wasm module with more than ~256k targets on one brtable instruction in a way that results in an incorrect conditional branch target. This conditional branch could then jump to arbitrary other code (at an user-controlled offset), leading to arbitrary sandbox escapes. Impact Any Wasmtime engine running on aarch64 with default settings can be forced to jump to arbitrary code by a user-controlled Wasm module. All versions of Wasmtime/Cranelift that support aarch64, since the initial release of that support in 2020 (before Wasmtime v1.0), are affected. Patches Wasmtime v36.0.19, v48.0.7, and v49.0.4 have been released which all fix this issue.
Proof-of-concept code is published
Public PoC
Signals come from Exploit-DB, Metasploit, Nuclei and published proof-of-concept repositories. Their absence means nothing was found, not that nothing exists.
Assessment
- CVSS
- 9.9 (v3.1)
- Severity
- Critical
- EPSS
- 0.0099% chance of exploitation in the next 30 days
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Public PoC
- Published
- 28 October 2026
- Last updated
- 28 October 2026
- Affected
- rust · wasmtime
- Weakness
- CWE-691
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
At the source
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-mghf-wjfp-p5xm
- https://nvd.nist.gov/vuln/detail/CVE-2026-115893
- https://github.com/bytecodealliance/wasmtime/pull/14818
- https://github.com/bytecodealliance/wasmtime/pull/14819
- https://github.com/bytecodealliance/wasmtime/pull/14820
- https://github.com/bytecodealliance/wasmtime/pull/14826
- https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abd
- https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618
- https://github.com/bytecodealliance/wasmtime/commit/e61df1b454be9313d61a5f8de07722a421139bbe
- https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa
- https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19
- https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7
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