Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction

Summary

## 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 `br_table` 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.

Remediation

1. Inventory every wasmtime deployment, including staging.
2. Upgrade wasmtime to the fixed version for your release line, listed under Affected versions.
3. Confirm the running version after the upgrade.

References

• Advisoryhttps://github.com/advisories/GHSA-mghf-wjfp-p5xm
• Referencehttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-mghf-wjfp-p5xm
• Referencehttps://nvd.nist.gov/vuln/detail/CVE-2026-115893
• Referencehttps://github.com/bytecodealliance/wasmtime/pull/14818
• Referencehttps://github.com/bytecodealliance/wasmtime/pull/14819
• Referencehttps://github.com/bytecodealliance/wasmtime/pull/14820
• Referencehttps://github.com/bytecodealliance/wasmtime/pull/14826
• Referencehttps://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abd
• Referencehttps://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618
• Referencehttps://github.com/bytecodealliance/wasmtime/commit/e61df1b454be9313d61a5f8de07722a421139bbe
• Referencehttps://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa
• Referencehttps://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19