CVE-2026-40912Public exploitNetwork attack vector

Authentication bypass via encoded path desynchronization

Published Apr 30, 2026 · Updated Apr 30, 2026

Authentication bypass in Traefik Proxy before 2.11.43, 3.6.14, or 3.7.0-rc.2 allows remote attackers to reach protected routes. StripPrefixRegex measures a match on the decoded URL path, then applies that byte length to the percent-encoded RawPath, leaving a dot segment that authentication sees as a different route. Exploitation requires StripPrefixRegex before ForwardAuth, BasicAuth, or DigestAuth and a backend that normalizes dot segments, exposing protected content without credentials.

CVSS severity7.8
High
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Traefik Proxy before 2.11.43, 3.6.14, or 3.7.0-rc.2 allows remote attackers to reach protected routes. StripPrefixRegex measures a match on the decoded URL path, then applies that byte length to the percent-encoded RawPath, leaving a dot segment that authentication sees as a different route. Exploitation requires StripPrefixRegex before ForwardAuth, BasicAuth, or DigestAuth and a backend that normalizes dot segments, exposing protected content without credentials.

The record

CVE
CVE-2026-40912
Published
Apr 30, 2026
Updated
Apr 30, 2026
Vendor
Traefik Labs
Product
Traefik Proxy
Classifications
CWE-22, CWE-706, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.11.43
  2. Affected versionversion=>= 3.0.0-beta1, < 3.6.14
  3. Affected versionversion=>= 3.7.0-ea.1, < 3.7.0-rc.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Traefik Labs · Traefik Proxyversion=< 2.11.43; version=>= 3.0.0-beta1, < 3.6.14; version=>= 3.7.0-ea.1, < 3.7.0-rc.2

Published CVSS scores

8.6Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
7.8GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N
8.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-706Use of Incorrectly-Resolved Name or Reference
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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