CVE-2020-15129

There exists a potential open redirect vulnerability in Traefik's handling of the X-Forwarded-Prefix header. Active Exploitation of this issue is unlikely as it would require active header injection, however the Traefik team addressed this issue nonetheless to prevent abuse in e.g. cache poisoning scenarios.

Details

The Traefik API dashboard component doesn't validate that the value of the header X-Forwarded-Prefix is a site relative path and will redirect to any header provided URI.

e.g.

$ curl --header 'Host:traefik.localhost' --header 'X-Forwarded-Prefix:https://example.org' 'http://localhost:8081'
<a href="https://example.org/dashboard/">Found</a>.`

Workarounds

By using the headers middleware, the request header X-Forwarded-Prefix value can be overridden by the value . (dot)

• https://docs.traefik.io/v2.2/middlewares/headers/#customrequestheaders
• https://docs.traefik.io/v1.7/basics/#custom-headers

For more information

If you have any questions or comments about this advisory, open an issue in Traefik.

Credit

This issue was found by the GitHub Application Security Team and reported on behalf of the GHAS by the GitHub Security Lab Team.

A successful exploitation of an open redirect can be used to entice victims to disclose sensitive information.

Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites. Typical impact: phishing and credential harvesting via a trusted domain.

CVE-2020-15129 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.7.26, 2.3.0-rc6, 2.2.8, 2.3.0-rc3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2020-15129? CVE-2020-15129 is a medium-severity open redirect vulnerability in github.com/traefik/traefik (go), affecting versions >= 1.5.0-rc5, < 1.7.26. It is fixed in 1.7.26, 2.3.0-rc6, 2.2.8, 2.3.0-rc3. Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites.
2. How severe is CVE-2020-15129? CVE-2020-15129 has a CVSS score of 6.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2020-15129?
   • github.com/traefik/traefik (go) (versions >= 1.5.0-rc5, < 1.7.26)
   • github.com/traefik/traefik/v2 (go) (versions < 2.2.8)
   • github.com/containous/traefik (go) (versions >= 1.5.0-rc5, < 1.7.26)
   • github.com/containous/traefik/v2 (go) (versions < 2.2.8)
   • github.com/traefik/traefik/api (go) (versions >= 1.5.0-rc5, < 1.7.26)
   • github.com/traefik/traefik/v2/pkg/api (go) (versions < 2.2.8)
   • github.com/containous/traefik/api (go) (versions >= 1.5.0-rc5, < 1.7.26)
   • github.com/containous/traefik/v2/pkg/api (go) (versions < 2.2.8)
4. Is there a fix for CVE-2020-15129? Yes. CVE-2020-15129 is fixed in 1.7.26, 2.3.0-rc6, 2.2.8, 2.3.0-rc3. Upgrade to this version or later.
5. Is CVE-2020-15129 exploitable, and should I be worried? Whether CVE-2020-15129 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2020-15129 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2020-15129?
   • Upgrade github.com/traefik/traefik to 1.7.26 or later
   • Upgrade github.com/traefik/traefik/v2 to 2.3.0-rc6 or later
   • Upgrade github.com/containous/traefik to 1.7.26 or later
   • Upgrade github.com/containous/traefik/v2 to 2.2.8 or later
   • Upgrade github.com/traefik/traefik/v2 to 2.3.0-rc6 or later
   • Upgrade github.com/containous/traefik/v2 to 2.3.0-rc3 or later
   • Upgrade github.com/traefik/traefik/api to 1.7.26 or later
   • Upgrade github.com/traefik/traefik/v2/pkg/api to 2.3.0-rc6 or later
   • Upgrade github.com/traefik/traefik/v2/pkg/api to 2.3.0-rc6 or later
   • Upgrade github.com/containous/traefik/api to 1.7.26 or later
   • Upgrade github.com/containous/traefik/v2/pkg/api to 2.2.8 or later
   • Upgrade github.com/containous/traefik/v2/pkg/api to 2.3.0-rc3 or later