# CVE-2026-54914: WebAssembly Micro Runtime: Heap Buffer Overflow in WAMR WASI poll_oneoff Output Buffer

Status: published. Published: 2026-11-05. Updated: 2026-11-05.

WebAssembly Micro Runtime (WAMR) is a lightweight standalone WebAssembly (Wasm) runtime. Prior to 2.4.5, wasi_poll_oneoff in core/iwasm/libraries/libc-wasi/libc_wasi_wrapper.c validates the output pointer for only one wasi_event_t, while wasmtime_ssp_poll_oneoff in core/iwasm/libraries/libc-wasi/sandboxed-system-primitives/src/posix.c can write as many events as the guest-controlled nsubscriptions value. A crafted guest module can provide multiple subscriptions that produce events while positioning an output region large enough for only one event, causing a later out[nevents] write to cross the validated Wasm linear-memory boundary into adjacent host heap memory. The overwrite contains partly attacker-controlled event data and can reliably crash the host process, with further confidentiality or integrity consequences depending on heap layout. This issue is fixed in version 2.4.5.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- bytecodealliance / wasm-micro-runtime: < 2.4.5 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 4.0: 8.3 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-122

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/wasm-micro-runtime/wasm-micro-runtime/security/advisories/GHSA-wj3p-xhqm-pffc (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/wasm-micro-runtime/wasm-micro-runtime/commit/1f98fb01d09b2ef5e49dc0be2e6006f962fd87f1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/wasm-micro-runtime/wasm-micro-runtime/commit/b49d10eac4176817305d60ea59d24bc69a53eb7b (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/wasm-micro-runtime/wasm-micro-runtime/releases/tag/WAMR-2.4.5 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-54914; retrieved 2026-11-05; source updated 2026-11-05

Revision: 2508f56b370c37d6672f861cc3ae43fd052fa550ca97bbe21faf5fed90f5d8f7

Canonical: https://y2.dev/cve/CVE-2026-54914

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