---
title: "CVE-2026-115893: Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction"
url: https://erroneo.us/security/cve/CVE-2026-115893/
description: "CVE-2026-115893 (bytecodealliance wasmtime): Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-10-23
date_modified: 2026-10-26
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-115893"
kev: false
cvss: 9.9
epss: 0.00432
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-115893: Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.4% , percentile 37: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 37% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Editorial verdict: Check exposure. Wasmtime: Two CVSS 9.9 Cranelift Sandbox Escapes — If you run WebAssembly you did not write, especially on ARM64, treat this as an urgent sandbox-escape fix and rebuild. If you only run your own trusted modules, update on a normal schedule.

## What it is

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 brtable 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.

## Affected products (CVE record)

- bytecodealliance wasmtime: < 36.0.19, >= 37.0.0, < 48.0.7, >= 49.0.0, < 49.0.4

## Severity

- GitHub_M CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- FIRST EPSS (model of 2026-10-26): 0.43% probability of exploitation activity in the next 30 days; percentile 37.

## Sources

- [CVE.org record CVE-2026-115893](https://www.cve.org/CVERecord?id=CVE-2026-115893)
- [NVD entry CVE-2026-115893](https://nvd.nist.gov/vuln/detail/CVE-2026-115893)
- [github.com](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-mghf-wjfp-p5xm)
- [github.com](https://github.com/bytecodealliance/wasmtime/pull/14818)
- [github.com](https://github.com/bytecodealliance/wasmtime/pull/14819)
- [github.com](https://github.com/bytecodealliance/wasmtime/pull/14820)
- [github.com](https://github.com/bytecodealliance/wasmtime/pull/14826)
- [github.com](https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abd)
- [github.com](https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618)
- [github.com](https://github.com/bytecodealliance/wasmtime/commit/e61df1b454be9313d61a5f8de07722a421139bbe)
- [github.com](https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa)
- [github.com](https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19)
- [github.com](https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7)
- [github.com](https://github.com/bytecodealliance/wasmtime/releases/tag/v49.0.4)

---
Source page: https://erroneo.us/security/cve/CVE-2026-115893/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt