# WASI preview 0 implementation of \`poll_oneoff\` circumvents fuel consumption

Advisory record · `GHSA-j366-h8gg-77pm`

- **Identifiers:** `GHSA-j366-h8gg-77pm` · `CVE-2026-115380` · `RUSTSEC-2026-0321`
- **State:** Confirmed
- **Severity:** CVSS 5.1 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-770](https://cwe.mitre.org/data/definitions/770.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 2 Oct 2026
- **Updated:** 24 Oct 2026
- **Reviewed by a person:** No

[Published by the maintainers](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-j366-h8gg-77pm) · not yet reviewed by GitHub. The bytecodealliance/wasmtime maintainers published this as a GitHub repository advisory; GitHub’s reviewed advisory replaces it here when it arrives.

Published by the bytecodealliance/wasmtime maintainers at 2 Oct 2026, 12:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `wasmtime-wasi` (crates.io): affected `>=0.0.0-0, <36.0.17 || >=37.0.0, <48.0.4 || >=49.0.0, <49.0.2`; fixed in `36.0.17`, `48.0.4`, `49.0.2`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The wasmtime-wasi crate is affected before 36.0.17, from 37.0.0 before 48.0.4, and from 49.0.0 before 49.0.2. Its WASI preview 0 implementation of poll_oneoff can bypass fuel consumption, and the source gives few details on what an attacker needs. Upgrade to 36.0.17, 48.0.4, or 49.0.2, matching your release line.

Written 3 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.1 Medium, CVSS 4.0: `CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`, from CNA (VulnCheck)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0012, the 1st percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 2 Oct 2026, 19:39 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-j366-h8gg-77pm)
- 31 Oct 2026, 14:24 UTC: First seen by agentprime
- 31 Oct 2026, 14:24 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/RUSTSEC-2026-0321)

## Sources

- [GitHub Advisory Database: GHSA-j366-h8gg-77pm](https://github.com/advisories/GHSA-j366-h8gg-77pm)
- [OSV: GHSA-j366-h8gg-77pm](https://osv.dev/vulnerability/GHSA-j366-h8gg-77pm)
- <https://crates.io/crates/wasmtime-wasi>
- <https://rustsec.org/advisories/RUSTSEC-2026-0321.html>
- <https://github.com/bytecodealliance/wasmtime/pull/14481>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-j366-h8gg-77pm>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-j366-h8gg-77pm/>. Everything for agents: <https://agentprime.io/llms.txt>.