Cyber Resilience

CVE-2026-32305

Auth Bypass in Traefik ≤ 2.11.41

Auth Bypass
Published
20 March 2026
Modified
15 July 2026
Patch / advisory
View advisory
CVSS Score v4 7.8
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/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
EPSS Score 0.0040 33th percentile
Risk Priority 43 floored blend · peak EPSS

Summary

CVE-2026-32305 is a high-severity Improper Authentication (CWE-287) vulnerability in Traefik Traefik. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Default Accounts (T1078.001); ranked at the 33th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to CM-2 (Baseline Configuration) and CM-6 (Configuration Settings) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Traefik is an HTTP reverse proxy and load balancer. Versions 2.11.40 and below, 3.0.0-beta1 through 3.6.11, and 3.7.0-ea.1 are vulnerable to mTLS bypass through the TLS SNI pre-sniffing logic related to fragmented ClientHello packets. When a TLS ClientHello is fragmented…

more

across multiple records, Traefik's SNI extraction may fail with an EOF and return an empty SNI. The TCP router then falls back to the default TLS configuration, which does not require client certificates by default. This allows an attacker to bypass route-level mTLS enforcement and access services that should require mutual TLS authentication. This issue is patched in versions 2.11.41, 3.6.11 and 3.7.0-ea.2.

CWE(s)
CWE-287CWE-1188CWE-179

Related Threats

MITRE ATT&CK Enterprise Techniques

T1078.001 Default Accounts Stealth
Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.
attack.mitre.org →
T1078 Valid Accounts Stealth
Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.
attack.mitre.org →
T1133 External Remote Services Persistence
Adversaries may leverage external-facing remote services to initially access and/or persist within a network.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1040 Network Sniffing Credential Access
Adversaries may passively sniff network traffic to capture information about an environment, including authentication material passed over the network.
attack.mitre.org →
T1134 Access Token Manipulation Stealth
Adversaries may modify access tokens to operate under a different user or system security context to perform actions and bypass access controls.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-48491Same product: Traefik Traefik
CVE-2026-53622Same product: Traefik Traefik
CVE-2026-48020Same product: Traefik Traefik
CVE-2026-39858Same product: Traefik Traefik
CVE-2026-54763Same product: Traefik Traefik
CVE-2026-41181Same product: Traefik Traefik
CVE-2025-66490Same product: Traefik Traefik
CVE-2026-41174Same product: Traefik Traefik
CVE-2023-47106Same product: Traefik Traefik
CVE-2026-65602Same product: Traefik Traefik

Affected Assets

traefik
traefik
3.7.0 · ≤ 2.11.41 · 3.0.0 — 3.6.11

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 21 hardening rules · 8 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V14.3.2
  • V1.3.6
  • V1.3.8
  • V2.2.1

Mitigating Controls (NIST 800-53 r5) AI

IA-2 Identification and Authentication (Organizational Users) good match

Mandates unique identification and authentication of organizational users before access, directly stopping improper authentication.

IA-3 Device Identification and Authentication good match

Requires unique identification and authentication of devices before establishing connections, preventing unauthenticated device claims.

IA-8 Identification and Authentication (Non-organizational Users) good match

Mandates unique identification and authentication of non-organizational users, directly addressing the weakness for external actors.

CM-2 Baseline Configuration good match

Baseline configuration directly requires documenting and maintaining secure initial settings instead of insecure defaults.

CM-6 Configuration Settings good match

Configuration settings mandate the most restrictive values be applied at initialization, eliminating reliance on insecure factory defaults.

IA-5 Authenticator Management good match

Manages authenticators with verification and secure distribution, reducing opportunities for improper authentication.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-01 full match
prevents

Hardened baselines and configuration management directly replace insecure defaults with secure settings.

PR.AA-03 mostly match
prevents

PR.AA-03 directly enforces authentication mechanisms that eliminate most improper-authentication defects, yet CWE-287 spans additional vectors (missing checks, flawed protocols, session handling) that one control does not fully close.

PR.AA-04 mostly match
prevents

PR.AA-04 directly enables verification of identity assertions (mostly preventing CWE-287 in that scope) yet leaves many other authentication failure modes unaddressed (only partial prevention overall).

PR.PS-06 mostly match
prevents

Secure development practices include designing products with secure defaults rather than insecure ones.

ID.RA-09 partial match
prevents

Pre-acquisition integrity checks can reject products known to ship with insecure defaults.

PR.AA-01 partial match
prevents

PR.AA-01 supplies and governs credentials/tokens that authentication relies on, removing some weak-credential cases, yet leaves verification logic, missing checks, and protocol flaws untouched.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.5 Secure authentication full match
prevents

Requiring authentication methods whose strength matches the sensitivity of the data and mandating multi-factor authentication directly blocks attempts to access resources without proving identity.

A.5.17 Authentication information mostly match
prevents

Verifying user identity before issuing replacement credentials and forcing changes after compromise reduces the likelihood that authentication bypass can be achieved through stolen or weak credentials.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect early-validation flaws but does not inherently prevent them in design.

A.8.9 Configuration management mostly match
prevents

Mandating secure baseline templates and immediate replacement of vendor defaults directly stops systems from being deployed with insecure factory settings that attackers can exploit.

A.5.16 Identity management partial match
prevents

Mandating segregated approval and oversight for non-human identities reduces the chance that weak or orphaned credentials can be exploited for unauthorized authentication.

A.8.21 Security of network services partial match
mitigates

Requiring authentication mechanisms and technical parameters for secure connections ensures that network services verify user identity before granting access, preventing exploitation of missing or weak authentication.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-287
  • V-248823 OL 8 must not have the telnet-server package installed. prevents CWE-1188
RHEL 7 (4 rules)
  • V-204627 SNMP community strings on the Red Hat Enterprise Linux operating system must be changed from the default. prevents CWE-1188
  • V-204425 The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon does not allow authentication using an empty password. prevents CWE-287
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-287
RHEL 8 (1 rule)
  • V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-287
Ubuntu 22.04 (2 rules)
  • V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-287
  • V-260529 Ubuntu 22.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements. prevents CWE-1188
Ubuntu 24.04 (3 rules)
  • V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-287
  • V-270708 Ubuntu 24.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements. prevents CWE-1188
  • V-270714 Ubuntu 24.04 LTS must not allow accounts configured in Pluggable Authentication Modules (PAM) with blank or null passwords. prevents CWE-287
Windows Server 2016 (1 rule)
  • V-224972 Active Directory Group Policy objects must have proper access control permissions. prevents CWE-1188
Windows Server 2019 (1 rule)
  • V-205741 Windows Server 2019 Active Directory Group Policy objects must have proper access control permissions. prevents CWE-1188

References