wasmtime has a panic when allocating a table exceeding the size of the host's address space

Exploitation

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

CVSS 4.0

5.9 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-44216: 0.32% estimated exploitation activity in the next 30 days; percentile 24.92 (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 Wasmtime's allocation logic for a WebAssembly table contained checked arithmetic which panicked on overflow. This overflow is possible to trigger, and thus panic, when a table with an extremely large size is allocated. This is possible with the WebAssembly memory64 proposal where tables can have sizes in the 64-bit range as opposed to the previous 32-bit range which would not overflow. The panic happens when attempting to create a very large table, such as when instantiating a WebAssembly module or component. This bug does not affect the pooling allocator which limits tables sizes to much less than the required amount to trigger the overflow. This bug is only present for the on-demand instance allocator, which is Wasmtime's default allocator. This bug also requires the memory64 WebAssembly feature to be enabled, which is on-by-default. Panicking in the host process is considered a denial-of-service vector for Wasmtime. Patches Wasmtime 36.0.8, 43.0.2, and 44.0.1 have all been…

Published by the source

7 May 2026, 00:08 UTC

Last modified by the source

14 May 2026, 20:49 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-p8xm-42r7-89xg

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# Patch Next advisory brief: CVE-2026-44216

Advisory: wasmtime has a panic when allocating a table exceeding the size of the host's address space
IDs: CVE-2026-44216, GHSA-p8xm-42r7-89xg
Record: https://patchnext.com/advisories/cve-2026-44216 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: wasmtime 43.0.2, 36.0.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io wasmtime: affected >= 30.0.0, < 36.0.8; >= 37.0.0, < 43.0.2; fixed in 36.0.8, 43.0.2

## 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-p8xm-42r7-89xg (GitHub-reviewed advisory GHSA-p8xm-42r7-89xg lists affected ranges: crates.io wasmtime >=30.0.0 =37.0.0 <43.0.2)

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