CVE-2026-48020
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedTraefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. This vulnerability is fixed in 2.11.48, 3.6.19, and 3.7.3.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceTraefik's StripPrefix middleware fails to properly normalize paths containing path traversal sequences (.. or %2e%2e). When a public router uses PathPrefix matching with StripPrefix, an attacker can craft requests that match the public route initially but resolve to protected backend paths after prefix stripping and normalization, bypassing authentication middleware on protected routers.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 2.11.48>= 3.0.0, < 3.6.19>= 3.7.0, < 3.7.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Traefik versionRun 'traefik version' or check the container/image version deployed in your environmentAffected if The version is < 2.11.48, or >= 3.0.0 and < 3.6.19, or >= 3.7.0 and < 3.7.3
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Locate StripPrefix middleware configurationsSearch Traefik configuration files (static and dynamic) for 'StripPrefix' middleware definitions, or check for 'stripprefix' label in docker-compose or Kubernetes annotationsAffected if StripPrefix middleware is defined and used in your router configuration
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Review routers using PathPrefix rulesExamine all router configurations with 'rule: PathPrefix(/...)' and identify which ones use the StripPrefix middlewareAffected if A router with PathPrefix rule is paired with StripPrefix middleware, allowing path manipulation
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Check for protected backend pathsInspect your router configurations to identify if any routers expose sensitive paths like /admin, /api, or internal endpointsAffected if Protected or internal paths are served by routers that could be reached via the path traversal technique
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Verify backend authentication existsReview whether backends behind StripPrefix-protected routers have their own authentication mechanismsAffected if Backends rely solely on Traefik routing for access control without additional backend-level authentication
You are affected if running a vulnerable Traefik version with StripPrefix middleware used on routers that expose sensitive paths, and those backends lack independent authentication controls.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped2.11.483.6.193.7.3
Upgrade Traefik to versions 2.11.48, 3.6.19, or 3.7.3 or later. Review existing router configurations using PathPrefix with StripPrefix to ensure no authentication bypass is possible.
Upgrade to Traefik 2.11.48, 3.6.19, or 3.7.3 depending on your current major version branch
- 1. Identify current Traefik version by running `traefik --version`
- 2. Determine the appropriate upgrade path based on current version: for 2.x versions < 2.11.48, upgrade to 2.11.48; for 3.0.0-3.6.x versions < 3.6.19, upgrade to 3.6.19; for 3.7.0-3.7.x versions < 3.7.3, upgrade to 3.7.3
- 3. Upgrade Traefik using the package manager or binary appropriate for your deployment (e.g., `docker pull traefik:v2.11.48`, `apt-get install traefik=2.11.48`, or download from github.com/traefik/traefik/releases/tag/v2.11.48)
- 4. Verify the upgrade was successful by running `traefik --version`
- 5. Review the router configurations that use StripPrefix middleware to ensure no unintended path normalization side effects affect your application
- 6. Test that authentication/authorization is properly enforced on protected routes after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-48020 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-48020 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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