GHSA-3p27-qvp9-27qf

ghsaUSosv

Wasmtime has a leak in WASIp1 `fd_renumber` implementation

view advisory published 2026-08-26Licence: CC-BY-4.0

### Impact Wasmtime's native implementation of WASIp1 suffers from a leak in the `fd_renumber` function where the file descriptor being renumbered to is not properly closed. Wasmtime's implementation erroneously only updated the table of descriptors for WASIp1 and didn't update the underlying table of descriptors used by the host. This behavior means that while `fd_renumber` works correctly from a guest's perspective it ends up leaking resources in the host that aren't cleaned up until the corresponding `Store` is destroyed. This means that guests can, in a loop, use `fd_renumber` to cause hosts to exhaust resources or exhaust file descriptors. This bug only affects the native implementation of WASIp1. This means that only runtimes which load core wasm modules and expose `fd_renumber` are affected. Runtimes are additionally only affected if they expose the ability to acquire a file descriptor, such as opening a file. For runtimes that deny access to files they are unaffected. ### Patches Wasmtime 24.0.10, 36.0.11, 44.0.3, and 45.0.2 have been released which fix this issue. ### Workarounds There are no workarounds for this issue and hosts are recommended to update.

01

describes (1)

Related CVEs.

IDseverity exploitable
CVE-2026-54786USmedium5.0—
Wasmtime is a runtime for WebAssembly. All versions prior to 24.0.10; versions 25.0.0 through those before 36.0.11; versions 37.0.0 through those before 44.0.3; and versions 45.0.…
02

references

External citations — patches, advisories, analysis.

scry

Advisories like this name the exposed products attackers go after on your perimeter. See what is exposed on your perimeter with a free passive scan.

Free scan