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Vulnerabilities

Security fix · CVE-2026-88877

Traefik is a HTTP reverse proxy and load balancer.

Published Sep 10, 2026 · catalog updated Oct 8, 2026 · Traefik is a HTTP

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-88877. EPSS is 0.65%. Act only if a listed version of Traefik is a 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 a HTTP).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Critical9.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.65%
Remediation
Version ranges on file
Affected products
cpe traefik/traefik

Traefik is a HTTP reverse proxy and load balancer. In versions >= v3.7.0 and <= v3.7.11, the Kubernetes ingress-nginx provider mishandles Ingresses that carry both an authentication annotation and the nginx.ingress.kubernetes.io/from-to-www-redirect annotation. For such Ingresses the provider creates an additional 'sibling' router that matches on the host alone, carries only the RedirectRegex middleware, and still points at the parent router's protected backend service. Because RedirectRegex is not a terminal handler, a request its pattern does not match is forwarded to the backend, and because the redirect pattern only accepts a numeric port while Traefik's host matcher canonicalizes the authority via net.SplitHostPort, a request with a non-numeric or empty port (for example 'Host: www.example.com:x') selects the sibling router, misses the redirect, and is proxied to the protected backend with none of the Ingress's annotation-derived middlewares applied. This discards not only authentication (e.g. BasicAuth) but every annotation-derived middleware, including source-IP allowlisting. Traefik v2 and v3 releases before v3.7.0 are not affected. The issue is fixed in v3.7.12.

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/traefik< 3.7.12

How to fix CVE-2026-88877

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-2026-88877. EPSS is 0.65%. Act only if a listed version of Traefik is a HTTP is installed.

Which versions are affected?

Compare what you have installed with < 3.7.12. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-639: Authorization Bypass Through User-Controlled Key. EPSS 0.65%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Nginx securityTraefik security

Code

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

Timeline

Detection, updates, and resolution for this record.

  1. Sep 10, 2026 · Monitored products — high

    Detected

    Traefik is a HTTP reverse proxy and load balancer. In versions >= v3.7.0 and <= v3.7.11, the Kubernetes ingress-nginx provider mishandles Ingresses that carry both an authentication annotation and the nginx.ingress.kubernetes.io/from-to-www-redirect annotation. For such Ingresses the provider creates an additional 'sibling' router that matches on the host alone, carries only the RedirectRegex midd

  2. Oct 8, 2026 · Monitored products — high

    Updated

    Traefik is a HTTP reverse proxy and load balancer. In versions >= v3.7.0 and <= v3.7.11, the Kubernetes ingress-nginx provider mishandles Ingresses that carry both an authentication annotation and the nginx.ingress.kubernetes.io/from-to-www-redirect annotation. For such Ingresses the provider creates an additional 'sibling' router that matches on the host alone, carries only the RedirectRegex midd

Sources

  • CVE.orgVulnerability recordCVE-2026-88877

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2026-88877

    Traefik is a HTTP reverse proxy and load balancer. In versions >= v3.7.0 and <= v3.7.11, the Kubernetes ingress-nginx provider mishandles Ingresses that carry both an authentication annotation and the nginx.ingress.kubernetes.io/from-to-www-redirect annotation. For such Ingresses the provider creates an additional 'sibling' router that matches on the host alone, carries only the RedirectRegex midd

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 5, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • Monitored products — highNov 2, 2026