CVE-2026-29054
Traefik 2.11.9 – 2.11.38
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NSummary
CVE-2026-29054 is a high-severity Improper Handling of Case Sensitivity (CWE-178) vulnerability in Traefik Traefik. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Masquerading (T1036); ranked at the 38th 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 AC-24 (Access Control Decisions) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-29054 is a vulnerability in Traefik, an HTTP reverse proxy and load balancer, affecting versions 2.11.9 through 2.11.37 and 3.1.3 through 3.6.8. The issue stems from incorrect handling of case sensitivity in Traefik's protection mechanism for X-Forwarded headers, such as X-Real-Ip, X-Forwarded-Host, X-Forwarded-Port, and others. When processing HTTP/1.1 requests, Traefik compares Connection header tokens case-sensitively against protected header names but deletes headers case-insensitively, enabling attackers to bypass the safeguard.
A remote unauthenticated attacker can exploit this vulnerability by crafting HTTP requests with lowercase Connection tokens, such as "Connection: x-real-ip", to remove Traefik-managed X-Forwarded identity headers before they reach backend services. This allows the attacker to strip critical client information like real IP addresses or hosts, potentially enabling IP spoofing or other integrity violations against downstream applications. The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N) and maps to CWE-178 (Improper Handling of Case Sensitivity).
Traefik has patched the issue in versions 2.11.38 and 3.6.9. Administrators should upgrade to these releases to mitigate the vulnerability. Additional details, including patch notes, are provided in the GitHub security advisory GHSA-92mv-8f8w-wq52 and release announcements for v2.11.38 and v3.6.9.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9848
Vulnerability Data
Traefik is an HTTP reverse proxy and load balancer. From version 2.11.9 to 2.11.37 and from version 3.1.3 to 3.6.8, there is a potential vulnerability in Traefik managing the Connection header with X-Forwarded headers. When Traefik processes HTTP/1.1 requests, the…
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protection put in place to prevent the removal of Traefik-managed X-Forwarded headers (such as X-Real-Ip, X-Forwarded-Host, X-Forwarded-Port, etc.) via the Connection header does not handle case sensitivity correctly. The Connection tokens are compared case-sensitively against the protected header names, but the actual header deletion operates case-insensitively. As a result, a remote unauthenticated client can use lowercase Connection tokens (e.g. Connection: x-real-ip) to bypass the protection and trigger the removal of Traefik-managed forwarded identity headers. This issue has been patched in versions 2.11.38 and 3.6.9.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Applying access control decisions to each request depends on accurate property determination that accounts for case differences.
Correct enforcement of authorizations for resource access structurally requires consistent case-sensitive handling of identifiers to avoid incorrect decisions.
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.
Secure SDLC practices can catch and prevent case-sensitivity flaws during code review or testing, but fixing one CWE achieves negligible coverage of the broad control.
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.
Secure SDLC practices should include case-sensitivity requirements in design and coding standards.
Application security requirements must specify case handling for identifiers and paths.
Architecture principles should enforce canonical, case-aware resource naming.
Secure coding guidelines must mandate explicit case handling to prevent inconsistent lookups.
Access-control rules that ignore case can allow unintended resource access.
Authentication logic must treat identifiers consistently to avoid bypass via case differences.