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Critical, CVSS 9.9amended

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

CVE-2026-115893GHSA-mghf-wjfp-p5xm

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (wasmtime 49.0.4, 48.0.7, 36.0.19), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • crates.io wasmtime

    Affected
    < 36.0.19>= 37.0.0, < 48.0.7>= 49.0.0, < 49.0.4
    Fixed in
    49.0.4, 48.0.7, 36.0.19

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.9 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS
  • CVE-2026-115893: 0.99% estimated exploitation activity in the next 30 days; percentile 62.56 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from osv record GHSA-mghf-wjfp-p5xm

  2. Revision 3 · amended ·

    Amended from ghsa record GHSA-mghf-wjfp-p5xm

  3. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  4. Revision 1 · created ·

    Published from osv record RUSTSEC-2026-0379

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-115893

Advisory: Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction
IDs: CVE-2026-115893, GHSA-mghf-wjfp-p5xm
Record: https://patchnext.com/advisories/rustsec-2026-0379 (revision 4, source checked 29 Oct 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: wasmtime 49.0.4, 48.0.7, 36.0.19. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io wasmtime: affected < 36.0.19; >= 37.0.0, < 48.0.7; >= 49.0.0, < 49.0.4; fixed in 49.0.4, 48.0.7, 36.0.19

## Suggested inspection (read-only)
- crates.io wasmtime: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on wasmtime.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/RUSTSEC-2026-0379 (OSV record RUSTSEC-2026-0379 lists affected ranges: crates.io wasmtime >=0.0.0-0 =37.0.0 =49.0.0 <49.0.4 (fixed))
- Verified: https://github.com/advisories/GHSA-mghf-wjfp-p5xm (GitHub-reviewed advisory GHSA-mghf-wjfp-p5xm lists affected ranges: crates.io wasmtime >=0 =37.0.0 =49.0.0 <49.0.4)
- Verified: https://osv.dev/vulnerability/GHSA-mghf-wjfp-p5xm (OSV record GHSA-mghf-wjfp-p5xm lists affected ranges: crates.io wasmtime >=0 =37.0.0 =49.0.0 <49.0.4 (fixed))

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