CVE-2026-54786
mediumpriority · track · 20EPSS 0.004 · 30 %ileEUUSEPSS · scored 2026-10-27
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 45.0.0 and 45.0.1 contain a native implementation of WASIp1 which 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. In a loop, guests can use fd_renumber to cause hosts to exhaust both resources and file descriptors. This bug only affects the native implementation of WASIp1, meaning 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. This issue has been fixed in versions 24.0.10, 36.0.11, 44.0.3, and 45.0.2.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 0.6–5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
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affected products (13)
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advisories (2)
Vendor and ecosystem advisories describing this.
- GHSA-3p27-qvp9-27qfWasmtime has a leak in WASIp1 `fd_renumber` implementation2026-08-26ghsa · osvUS
### 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.
- RUSTSEC-2026-0182Leak in WASIp1 `fd_renumber` implementation2026-06-15vendor · osvUS
This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-3p27-qvp9-27qf For more information see the GitHub-hosted security advisory.
also known as (4)
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sources
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references (3)
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