# 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. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 29 Mar 2026 - **Also known as:** GO-2026-4897 ## 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](https://github.com/traefik/traefik/issues).
Original Description ### 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
---------- ## 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 | Ecosystem | 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 | | `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. ## 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. ## Fix prompt for AI coding agents ```text Check this codebase for GHSA-46wh-3698-f2cx and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of GHSA-46wh-3698-f2cx in the wild and no public exploit code. Affected packages and fixed versions: - github.com/traefik/traefik/v3 (Go): affected from 3.0.0-beta3; fixed in 3.6.12, 3.7.0-ea.3 - github.com/traefik/traefik/v3 (Go): affected from 3.0.0-beta3; fixed in 3.6.12 - github.com/traefik/traefik/v3 (Go): affected from 3.0.0-beta3; fixed in 3.6.12 - github.com/traefik/traefik/v3 (Go): affected from 3.7.0-ea.1; fixed in 3.7.0-ea.3 - github.com/traefik/traefik/v3 (Go): affected from 3.7.0-ea.1; fixed in 3.7.0-ea.3 - github.com/traefik/traefik (Go): affected all versions; no fix listed - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.11.42 - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.11.42 - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.11.42 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/GHSA-46wh-3698-f2cx/ (Markdown: https://insights.sbomify.com/GHSA-46wh-3698-f2cx/index.md) ``` ## Sources - OSV: https://osv.dev/vulnerability/GHSA-46wh-3698-f2cx --- From sbomify Insights: https://insights.sbomify.com/GHSA-46wh-3698-f2cx/ Summaries are generated and may contain mistakes; the official description above is the record.