CVE-2026-32305
Description
A flaw was found in Traefik, an HTTP reverse proxy and load balancer. A remote attacker can exploit this vulnerability by sending fragmented ClientHello packets during the Transport Layer Security (TLS) handshake. This causes Traefik's Server Name Indication (SNI) extraction to fail, leading to a fallback to a default TLS configuration that does not require client certificates. This allows an attacker to bypass mutual TLS (mTLS) authentication, gaining unauthorized access to services that should be protected by client certificate requirements.
Mitigation
To mitigate unauthorized access, restrict network access to the Traefik instance to only trusted clients and networks. Implement firewall rules to limit inbound connections to the ports Traefik listens on for mTLS-protected services. For example, using `firewalld`, specific source IP addresses or networks can be allowed. After applying firewall rules, ensure the firewall service is reloaded for changes to take effect. This reduces the attack surface by preventing untrusted external access to the Traefik instance.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.3 | 5.3 | 8.3 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Changed | Unchanged | Changed |
| Confidentiality | Low | Low | Low |
| Integrity Impact | Low | None | Low |
| Availability Impact | Low | None | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
Understanding the Weakness (CWE)
Access Control,Integrity
Technical Impact: Bypass Protection Mechanism; Execute Unauthorized Code or Commands
An attacker could include dangerous input that bypasses validation protection mechanisms which can be used to launch various attacks including injection attacks, execute arbitrary code or cause other unintended behavior.
Frequently Asked Questions
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