How severe is CVE-2020-15129?

CVE-2020-15129 has a CVSS score of 4.7/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-15129?

CVE-2020-15129 affects the following packages: github.com/traefik/traefik (Go), github.com/traefik/traefik/v2 (Go), github.com/containous/traefik (Go), github.com/containous/traefik/v2 (Go), github.com/traefik/traefik/v2 (Go), github.com/containous/traefik/v2 (Go), github.com/traefik/traefik/api (Go), github.com/traefik/traefik/v2/pkg/api (Go), and 4 more. Ecosystems affected: Go.

How do I fix CVE-2020-15129?

Update github.com/traefik/traefik to 1.7.26 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15129 is resolved across your whole dependency graph.

How do I detect CVE-2020-15129 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-15129 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2020-15129 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-15129 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-15129?

CVE-2020-15129 has an EPSS (Exploit Prediction Scoring System) score of 8.0%, placing it in the 95th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-15129?

CVE-2020-15129 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2020-15129?

A Nuclei detection template exists for CVE-2020-15129, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2020-15129 published, and has it been updated?

CVE-2020-15129 was published on July 30, 2020 and was last updated on August 7, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2020-15129 — traefik

MEDIUMFix: containous/traefik@e63db78

CVE-2020-15129 is a medium-severity (CVSS 4.7) Open Redirect vulnerability in github.com/traefik/traefik. A fix is available for github.com/traefik/traefik — see the affected versions and patch details below.

Traefik vulnerable to Open Redirect via handling of X-Forwarded-Prefix header

Also known asGHSA-6qq8-5wq3-86rp

Published

Jul 30, 2020

Updated

Aug 7, 2026

Affected

12 pkgs

Patched

12 / 12

Exploits

None indexed

Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

8.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs95th percentile — riskier than 95% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-15129 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

12 pkgs affected

🐹github.com/traefik/traefik🐹github.com/traefik/traefik/v2🐹github.com/containous/traefik🐹github.com/containous/traefik/v2🐹github.com/traefik/traefik/v2🐹github.com/containous/traefik/v2🐹github.com/traefik/traefik/api🐹github.com/traefik/traefik/v2/pkg/api+4 more

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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>.`

Impact

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

Workarounds

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

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.

Affected Packages

12 total 12 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/traefik/traefik`	≥ 1.5.0-rc5&&< 1.7.26	1.7.26`go get github.com/traefik/traefik@v1.7.26`
🐹Go	`github.com/traefik/traefik/v2`	all versions	2.3.0-rc6`go get github.com/traefik/traefik/v2@v2.3.0-rc6`
🐹Go	`github.com/containous/traefik`	≥ 1.5.0-rc5&&< 1.7.26	1.7.26`go get github.com/containous/traefik@v1.7.26`
🐹Go	`github.com/containous/traefik/v2`	all versions	2.2.8`go get github.com/containous/traefik/v2@v2.2.8`
🐹Go	`github.com/traefik/traefik/v2`	≥ 2.3.0-rc1&&< 2.3.0-rc6	2.3.0-rc6`go get github.com/traefik/traefik/v2@v2.3.0-rc6`
🐹Go	`github.com/containous/traefik/v2`	≥ 2.3.0-rc1&&< 2.3.0-rc3	2.3.0-rc3`go get github.com/containous/traefik/v2@v2.3.0-rc3`

Affected Products

1 product · 5 configurations

Application

traefiktraefik

≥ 2.2.0 && < 2.2.8

1 version

2.3.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/traefik/traefik to 1.7.26 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15129 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

How to detect CVE-2020-15129

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2020-15129 -u https://target

Template: Traefik - Open Redirect
Severity: medium
Impact: An attacker can manipulate the redirect URL and trick users into visiting malicious websites.
Remediation: Apply the vendor-provided patch or upgrade to a non-vulnerable version of Traefik.

Template by ProjectDiscovery nuclei-templates (dwisiswant0), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

## Summary 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://e