# CVE-2026-32305: Traefik mTLS bypass via fragmented ClientHello SNI extraction failure > Attackers can bypass mutual TLS authentication in Traefik by sending fragmented ClientHello packets, accessing protected services without valid client certificates. - **Severity:** High 7.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 20 Mar 2026 - **Updated:** 15 Jul 2026 - **Also known as:** CLEANSTART-2026-SJ19949, GHSA-wvvq-wgcr-9q48, GO-2026-4793, MINI-3h24-53p3-6r9f, MINI-h563-q5ch-pwc4, MINI-vh5g-pvf6-hq8x ## What is CVE-2026-32305? CVE-2026-32305 is a high-severity authentication bypass vulnerability in Traefik Traefik, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Traefik is an HTTP reverse proxy and load balancer. Versions 2.11.40 and below, 3.0.0-beta1 through 3.6.11, and 3.7.0-ea.1 are vulnerable to mTLS bypass through the TLS SNI pre-sniffing logic related to fragmented ClientHello packets. When a TLS ClientHello is fragmented across multiple records, Traefik's SNI extraction may fail with an EOF and return an empty SNI. The TCP router then falls back to the default TLS configuration, which does not require client certificates by default. This allows an attacker to bypass route-level mTLS enforcement and access services that should require mutual TLS authentication. This issue is patched in versions 2.11.41, 3.6.11 and 3.7.0-ea.2. Weakness: CWE-179 (Incorrect Behavior Order: Early Validation), CWE-287 (Improper Authentication), CWE-1188 (Initialization of a Resource with an Insecure Default) ## Which versions are affected by CVE-2026-32305? 11 open source packages ship an affected version, including github.com/traefik/traefik/v3, github.com/traefik/traefik and github.com/traefik/traefik/v2. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/traefik/traefik/v3` | Go | All versions | 3.6.11, 3.7.0-ea.2 | | `github.com/traefik/traefik/v3` | Go | All versions | 3.6.11 | | `github.com/traefik/traefik/v3` | Go | All versions | 3.6.11 | | `github.com/traefik/traefik/v3` | Go | From 3.7.0-ea.1 | 3.7.0-ea.2 | | `github.com/traefik/traefik/v3` | Go | From 3.7.0-ea.1 | 3.7.0-ea.2 | | `github.com/traefik/traefik` | Go | All versions | None | | `github.com/traefik/traefik` | Go | All versions to 1.7.34 | None | | `github.com/traefik/traefik` | Go | All versions to 1.7.34 | None | | `github.com/traefik/traefik/v2` | Go | All versions | 2.11.41 | | `github.com/traefik/traefik/v2` | Go | All versions | 2.11.41 | | `github.com/traefik/traefik/v2` | Go | All versions | 2.11.41 | Products: Traefik Traefik. ## How do I fix CVE-2026-32305? Upgrade github.com/traefik/traefik/v3 to a fixed version for your release line: 3.6.11 or 3.7.0-ea.2. ## Is CVE-2026-32305 being exploited? There is no known exploitation of CVE-2026-32305 in the wild and no public exploit code. ## Other vulnerabilities in Traefik Traefik - [CVE-2024-45410](https://insights.sbomify.com/CVE-2024-45410/): HTTP client can remove the X-Forwarded headers in Traefik (critical 9.8) - [CVE-2026-88877](https://insights.sbomify.com/CVE-2026-88877/): Traefik v3.7.0 Authentication Bypass via from-to-www-redirect (critical 9.3) - [CVE-2026-85595](https://insights.sbomify.com/CVE-2026-85595/): Traefik before v2.11.55 and v3.0.0 through v3.7.10 Authentication Bypass via digestAuth (critical 9.3) - [CVE-2026-88007](https://insights.sbomify.com/CVE-2026-88007/): Traefik HTTP/3 Backend NTLM Connection Reuse (critical 9.1) - [CVE-2026-88009](https://insights.sbomify.com/CVE-2026-88009/): Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing path-scoped routing, middleware guards and access logging (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-32305 and fix it if it is affected. What it is: CVE-2026-32305 is a high-severity authentication bypass vulnerability in Traefik Traefik, published on 20 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 CVE-2026-32305 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/traefik/traefik/v3 (Go): affected all versions; fixed in 3.6.11, 3.7.0-ea.2 - github.com/traefik/traefik/v3 (Go): affected all versions; fixed in 3.6.11 - github.com/traefik/traefik/v3 (Go): affected all versions; fixed in 3.6.11 - github.com/traefik/traefik/v3 (Go): affected from 3.7.0-ea.1; fixed in 3.7.0-ea.2 - github.com/traefik/traefik/v3 (Go): affected from 3.7.0-ea.1; fixed in 3.7.0-ea.2 - github.com/traefik/traefik (Go): affected all versions; no fix listed - github.com/traefik/traefik (Go): affected all versions up to 1.7.34; no fix listed - github.com/traefik/traefik (Go): affected all versions up to 1.7.34; no fix listed - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.11.41 - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.11.41 - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.11.41 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/CVE-2026-32305/ (Markdown: https://insights.sbomify.com/CVE-2026-32305/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-32305 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-32305 - OSV: https://osv.dev/vulnerability/CVE-2026-32305 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-32305/ Summaries are generated and may contain mistakes; the official description above is the record.