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Vulnerabilities

Vulnerability · CVE-2026-41263

Traefik is an HTTP reverse proxy and load balancer.

Published Apr 30, 2026 · catalog updated Jun 17, 2026 · Traefik is an HTTP

Check if you run it

No confirmed exploitation is on record for CVE-2026-41263. EPSS is 0.41%. Act only if a listed version of Traefik is an HTTP is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Traefik is an HTTP).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.41%
Remediation
Advisory link
Affected products
cpe traefik/traefik

Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences. The variable intended to hold a constant-time fallback secret always resolves to an empty string, causing the constant-time comparison to short-circuit in microseconds rather than performing a full bcrypt evaluation. This restores the original timing oracle and makes it possible to distinguish existing users from non-existing ones by measuring authentication response times. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe traefik/traefik3.7.0

How to fix CVE-2026-41263

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-41263. EPSS is 0.41%. Act only if a listed version of Traefik is an HTTP is installed.

Which versions are affected?

Compare what you have installed with 3.7.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-208. EPSS 0.41%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 30, 2026 · NIST NVD

    Detected

    Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences. The variable intended to hold a constant-time fallback secret always resolves to an empty string, causing the constant-time compar

  2. Jun 17, 2026 · NIST NVD

    Updated

    Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences. The variable intended to hold a constant-time fallback secret always resolves to an empty string, causing the constant-time compar

Sources

  • CVE.orgVulnerability recordCVE-2026-41263

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-41263

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-41263

    Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences. The variab

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.