# A flaw was found in openstack-neutron's default Open vSwitch firewall rules. By sending carefully crafted packets, anyone in control of a server instance connected to the virtual switch can imperso... Advisory record · `GHSA-w8hx-f868-pvch` - **Identifiers:** `GHSA-w8hx-f868-pvch` · `CVE-2021-20267` · `PYSEC-2021-136` - **State:** Confirmed - **Severity:** No CVSS score - **Critical:** No - **Weakness (CWE):** [CWE-345](https://cwe.mitre.org/data/definitions/345.html) - **Tags:** [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md) - **Published:** 28 May 2021 - **Updated:** 10 Jun 2026 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 28 May 2021, 19:15 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `neutron` (PyPI): affected `<15.3.3 || >=16.0.0, <16.3.1 || >=17.0.0, <17.1.1`; fixed in `15.3.3`, `16.3.1`, `17.1.1` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > The neutron package (OpenStack networking) is vulnerable in versions before 15.3.3, from 16.0.0 before 16.3.1, and from 17.0.0 before 17.1.1, specifically its default Open vSwitch firewall rules. An attacker who controls a server instance connected to the virtual switch can send crafted packets to impersonate IPv6 addresses of other systems, which may cause denial of service or, in some cases, interception of traffic meant for other destinations. Only deployments using the Open vSwitch driver are affected. Upgrade to 15.3.3, 16.3.1, or 17.1.1 depending on your release line. Written 10 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 No source has published a CVSS score for this record yet. - **CISA KEV:** Not listed. - **EPSS:** 0.010, the 64th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline This record came from the full history of the GitHub Advisory Database, published 28 May 2021. New records show when each source confirmed them. ## Sources - [GitHub Advisory Database: GHSA-w8hx-f868-pvch](https://github.com/advisories/GHSA-w8hx-f868-pvch) - [OSV: GHSA-w8hx-f868-pvch](https://osv.dev/vulnerability/GHSA-w8hx-f868-pvch) - 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: .