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Fencer Intel
high 8.2

CVE-2026-35051 json

Traefik: ForwardAuth trustForwardHeader=false allows spoofed X-Forwarded-Prefix to bypass auth

published 6mo ago modified 3mo ago also EUVD-2026-26426 , GHSA-6384-m2mw-rf54 , GO-2026-5163

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

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 an authentication bypass vulnerability in Traefik's ForwardAuth middleware when trustForwardHeader=false is configured and Traefik is deployed behind a trusted upstream proxy. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

Patch / fix

  • go github.com/traefik/traefik/v3 3.6.14, 3.7.0-rc.2
  • go github.com/traefik/traefik/v2 2.11.43
  • Red Hat Red Hat OpenShift Dev Spaces 3.28 1779786779
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • traefik openSUSE Tumbleweed 3.6.15-1.1
  • traefik2 openSUSE Tumbleweed 2.11.44-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:10697-1openSUSE-SU-2026:10698-1

Is CVE-2026-35051 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-35051 updated cvss 8.2

Traefik: github.com/traefik/traefik: Traefik: Authentication bypass in ForwardAuth middleware

  • Red Hat OpenShift Dev Spaces 3.28 devspaces/traefik-rhel9 1779786779
    fixed: vendor fix RHSA-2026:21772
  • Red Hat OpenShift Dev Spaces 3.28 devspaces/udi-rhel9 1779829736, devspaces/code-rhel9 1779814592, devspaces/server-rhel9 1779342423, devspaces/openvsx-rhel9 1779528224, devspaces/udi-base-rhel9 1779741066, devspaces/code-sshd-rhel9 1779813519, +9 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
6mo ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/traefik/traefik/security/advisories/GHSA-6384-m2mw-rf54 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.8 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
CISA ADP 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
GitHub 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
CNA 4.0 7.8 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/traefik/traefik/v3
>=3.7.0-ea.1, <3.7.0-rc.2
>=3.0.0-beta1, <3.6.14
3.7.0-rc.2
3.6.14
go github.com/traefik/traefik/v2
<2.11.43
2.11.43
go github.com/traefik/traefik
<=1.7.34
all versions
 no fix listed

Affected products

  • traefik traefik
  • Red Hat Red Hat OpenShift Dev Spaces 3.28

Classification

Weakness
  • CWE-345 Insufficient Verification of Data Authenticity
  • CWE-501 Trust Boundary Violation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.