CyberSecBulletin
CVE-2026-40912NVD status: Modified

traefik: Use of Incorrectly-Resolved Name or Reference

Published Updated By the CyberSecBulletin desk

CVE-2026-40912 is a high-severity use of incorrectly-resolved name or reference vulnerability in traefik, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected traefik versions: < 2.11.43; >= 3.0.0-beta1, < 3.6.14; >= 3.7.0-ea.1, < 3.7.0-rc.2. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.77% chance of exploitation within 30 days, higher than 56% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of traefik you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Traefiktraefik< 2.11.43; >= 3.0.0-beta1, < 3.6.14; >= 3.7.0-ea.1, < 3.7.0-rc.2Not stated
Red HatRed Hat OpenShift Dev Spaces 3.28Not specified in the recordNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
LowLimited modification of data is possible.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.07.8HighCNA (github.com)
CVSS 3.18.2HighNVD
CVSS 3.18.6HighCNA

Official description

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 high severity authentication bypass vulnerability in Traefik's StripPrefixRegex middleware when used in combination with ForwardAuth, BasicAuth, or DigestAuth. The middleware matches the regex against the decoded URL path but uses the resulting byte length to slice the percent-encoded raw path. When a dot (or multiple dots) appears in the prefix portion of the URL, the raw path after stripping becomes a dot-segment (e.g. /./admin/secret). ForwardAuth receives this dot-segment path in X-Forwarded-Uri, which does not match the protected path patterns and therefore allows the request through. The backend then normalizes the dot-segment to the real path per RFC 3986 and serves the protected content An unauthenticated attacker can exploit this against any backend that performs dot-segment normalization. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use of Incorrectly-Resolved Name or Reference

The product uses a name or reference to access a resource, but the name/reference resolves to a resource that is outside of the intended control sphere.

More Use of Incorrectly-Resolved Name or Reference vulnerabilities (CWE-706)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in traefik

All traefik vulnerabilities

Recent Use of Incorrectly-Resolved Name or Reference vulnerabilities

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