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CVE-2026-85597· NVD / CVE Program· CNA VulnCheck

Traefik before v2.11.55 and v3.0.0 through v3.7.10 mTLS Bypass via TLS Option Conflict

Traefik before v2.11.55 and v3.0.0 through v3.7.10 contain a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts.

HighCVSS 8.2 · v4.0—No exploit Fix available
Published
Sep 4, 2026
Updated
Sep 16, 2026
EPSS
0.4% · 26th percentile
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Report tools

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Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.2 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
8.2
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
traefiktraefik

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • traefik traefikbefore 2.11.55
  • traefik traefik3.0.0 and later · before 3.7.11

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • traefik traefik

    • 2.11.55not affected
    • before 2.11.55affected · semver
    • 3.0.0 and later · up to and including 3.7.10affected · semver

Same product

traefik: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-88877Traefik v3.7.0 Authentication Bypass via from-to-www-redirect
    37Monitor
  • CVE-2026-85595Traefik before v2.11.55 and v3.0.0 through v3.7.10 Authentication Bypass via digestAuth
    37Monitor
  • CVE-2026-88007Traefik HTTP/3 Backend NTLM Connection Reuse
    36Monitor
  • CVE-2026-88009Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing path-scoped routing, middleware guards and access logging
    35Monitor
  • CVE-2025-32431Traefik has a possible vulnerability with the path matchers
    35Monitor
  • CVE-2023-54365Traefik - Denial of Service via HTTP/2 Request Handling
    34Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
traefik traefik2.11.55Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6560144 days apartTraefik before 3.7.7 Namespace Confusion via HTTPRoute ExtensionRef
    21Monitor
  • CVE-2026-6560244 days apartTraefik before 3.6.23 IngressRouteTCP ServersTransport Namespace Bypass
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/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-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records