# Guest controlled-size host heap allocation through WASIp3 streams Advisory record · `GHSA-x84v-gj2h-g759` - **Identifiers:** `GHSA-x84v-gj2h-g759` · `CVE-2026-115391` · `RUSTSEC-2026-0268` - **State:** Confirmed - **Severity:** CVSS 6.9 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:** 20 Aug 2026 - **Updated:** 24 Oct 2026 - **Reviewed by a person:** No [Published by the maintainers](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-x84v-gj2h-g759) · 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 20 Aug 2026, 12:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `wasmtime` (crates.io): affected `>=46.0.0, <46.0.3 || >=47.0.0, <47.0.4`; fixed in `46.0.3`, `47.0.4` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > Wasmtime versions 46.0.0 to before 46.0.3 and 47.0.0 to before 47.0.4 are affected. A guest program running inside Wasmtime can control the size of a host heap allocation through WASIp3 streams, which can cause excessive host memory use. The source gives few details on the exact impact or required conditions. Upgrade to Wasmtime 46.0.3 or 47.0.4, or later. 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 - 6.9 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H`, from CNA (VulnCheck) - **CISA KEV:** Not listed. - **EPSS:** 0.0017, the 6th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 20 Aug 2026, 17:59 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-x84v-gj2h-g759) - 22 Oct 2026, 19:13 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-115391) - 22 Oct 2026, 19:17 UTC: [Confirmed by NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-115391) - 31 Oct 2026, 14:24 UTC: First seen by agentprime - 31 Oct 2026, 14:24 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/RUSTSEC-2026-0268) ## Sources - [GitHub Advisory Database: GHSA-x84v-gj2h-g759](https://github.com/advisories/GHSA-x84v-gj2h-g759) - [OSV: GHSA-x84v-gj2h-g759](https://osv.dev/vulnerability/GHSA-x84v-gj2h-g759) - - - 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 (), 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: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .