Invalid drop of partially-initialized instances in the pooling instance allocator for modules with defined externref globals

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.1 · CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2022-23636: 0.77% estimated exploitation activity in the next 30 days; percentile 55.72 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact There exists a bug in the pooling instance allocator in Wasmtime's runtime where a failure to instantiate an instance for a module that defines an externref global will result in an invalid drop of a VMExternRef via an uninitialized pointer. As instance slots may be reused between consecutive instantiations, the value of the uninitialized pointer may be from a previous instantiation and therefore under the control of an attacker via a module's initial values for its globals. If the attacker can somehow determine an address under their control inside the mapped memory representing the instance pool, it is possible to trick the runtime to call dropinplace on a trait object under the attacker's control and therefore cause remote code execution. Exploiting the bug to cause remote code execution would be very difficult as attackers cannot determine the addresses of globals from code executing within the WebAssembly VM and the memory space for the instance pool cannot be statically…

Published by the source

16 Feb 2022, 22:35 UTC

Last modified by the source

2 May 2025, 12:48 UTC

Source last checked

26 Oct 2026, 15:38 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-88xq-w8cq-xfg7

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# Patch Next advisory brief: CVE-2022-23636

Advisory: Invalid drop of partially-initialized instances in the pooling instance allocator for modules with defined `externref` globals
IDs: CVE-2022-23636, GHSA-88xq-w8cq-xfg7
Record: https://patchnext.com/advisories/cve-2022-23636 (revision 1, source checked 26 Oct 2026, 15:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: wasmtime 0.34.1, 0.33.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io wasmtime: affected >= 0.34.0, <= 0.34.0; < 0.33.1; fixed in 0.34.1, 0.33.1

## 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://github.com/advisories/GHSA-88xq-w8cq-xfg7 (GitHub-reviewed advisory GHSA-88xq-w8cq-xfg7 lists affected ranges: crates.io wasmtime >=0.34.0 =0 <0.33.1)

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