GHSA-46wh-3698-f2cx Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)
Unauthenticated attackers can bypass Traefik deny rules by sending gRPC requests with malformed paths, requiring a fallback allow rule.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-46wh-3698-f2cx?
GHSA-46wh-3698-f2cx is an authentication bypass vulnerability in github.com/traefik/traefik, published on 29 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Summary
There is a potential vulnerability in Traefik due to its dependency on an affected version of gRPC-Go (CVE-2026-33186).
A remote, unauthenticated attacker can send gRPC requests with a malformed HTTP/2 :path pseudo-header omitting the mandatory leading slash (e.g., Service/Method instead of /Service/Method). While the server routes such requests correctly, path-based authorization interceptors evaluate the raw non-canonical path and fail to match "deny" rules, allowing the request to bypass the policy entirely if a fallback "allow" rule is present.
Patches
- https://github.com/traefik/traefik/releases/tag/v2.11.42
- https://github.com/traefik/traefik/releases/tag/v3.6.12
- https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3
For more information
If there are any questions or comments about this advisory, please open an issue.
<details> <summary>Original Description</summary>
Summary
This CVE hits traefik until Version 3.6.11 and 2.11.41. gRPC-Go has an authorization bypass via missing leading slash in :path
Details
As described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3
PoC
Update library version in https://github.com/traefik/traefik/blob/67c64ed9b25fbb90f1086977a62827133a7aa01b/go.mod#L108
Impact
Is described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3
</details>
Which versions are affected by GHSA-46wh-3698-f2cx?
9 open source packages ship an affected version, including github.com/traefik/traefik/v3, github.com/traefik/traefik and github.com/traefik/traefik/v2.
| Package | Affected | Fixed in |
|---|---|---|
github.com/traefik/traefik/v3 Go | From 3.0.0-beta3 | 3.6.12, 3.7.0-ea.3 |
github.com/traefik/traefik/v3 Go | From 3.0.0-beta3 | 3.6.12 |
github.com/traefik/traefik/v3 Go | From 3.0.0-beta3 | 3.6.12 |
github.com/traefik/traefik/v3 Go | From 3.7.0-ea.1 | 3.7.0-ea.3 |
github.com/traefik/traefik/v3 Go | From 3.7.0-ea.1 | 3.7.0-ea.3 |
github.com/traefik/traefik Go | All versions | None |
3 more packages
github.com/traefik/traefik/v2 Go | All versions | 2.11.42 |
github.com/traefik/traefik/v2 Go | All versions | 2.11.42 |
github.com/traefik/traefik/v2 Go | All versions | 2.11.42 |
How do I fix GHSA-46wh-3698-f2cx?
Upgrade github.com/traefik/traefik/v3 to a fixed version for your release line: 3.6.12 or 3.7.0-ea.3.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is GHSA-46wh-3698-f2cx being exploited?
There is no known exploitation of GHSA-46wh-3698-f2cx in the wild and no public exploit code.
Sources
Also known as GO-2026-4897.