# Missing TLS certificate verification in faye-websocket

Advisory record · `GHSA-2v5c-755p-p4gv`

- **Identifiers:** `GHSA-2v5c-755p-p4gv` · `CVE-2020-15133`
- **State:** Confirmed
- **Severity:** CVSS 8.0 High
- **Critical:** No
- **Weakness (CWE):** [CWE-295](https://cwe.mitre.org/data/definitions/295.html)
- **Tags:** [Weak cryptography or TLS](https://agentprime.io/advisories/tag/weak-crypto.md)
- **Published:** 31 Jul 2020
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 31 Jul 2020, 17:40 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `faye-websocket` (RubyGems): affected `<0.11.0`; fixed in `0.11.0`

## Machine-written summary

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

> Faye::WebSocket::Client in the faye-websocket package before 0.11.0 does not verify the server's TLS certificate for wss: connections. An attacker able to intercept the network path, such as a man-in-the-middle, can impersonate the server. Upgrade faye-websocket to version 0.11.0 or later; no workaround is listed, and the source says the verify_peer option only takes effect with a verifying ssl_verify_peer implementation.

Written 8 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

- 8.0 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0092, the 60th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:16 UTC: First seen by agentprime
- 31 Oct 2026, 15:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-2v5c-755p-p4gv)

## Sources

- [GitHub Advisory Database: GHSA-2v5c-755p-p4gv](https://github.com/advisories/GHSA-2v5c-755p-p4gv)
- [OSV: GHSA-2v5c-755p-p4gv](https://osv.dev/vulnerability/GHSA-2v5c-755p-p4gv)
- <https://github.com/faye/faye-websocket-ruby/security/advisories/GHSA-2v5c-755p-p4gv>
- <https://nvd.nist.gov/vuln/detail/CVE-2020-15133>
- <https://github.com/eventmachine/eventmachine/issues/275>
- <https://github.com/eventmachine/eventmachine/issues/814>
- <https://github.com/faye/faye/issues/524>
- <https://github.com/eventmachine/eventmachine/pull/378>
- <https://github.com/faye/faye-websocket-ruby/pull/129>
- <https://github.com/igrigorik/em-http-request/pull/340>
- <https://blog.jcoglan.com/2020/07/31/missing-tls-verification-in-faye>
- <https://github.com/faye/faye-websocket-ruby>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/faye-websocket/CVE-2020-15133.yml>
- <https://securitylab.github.com/advisories/GHSL-2020-094-igrigorik-em-http-request>

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-2v5c-755p-p4gv>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-2v5c-755p-p4gv/>. Everything for agents: <https://agentprime.io/llms.txt>.