Traefik entrypoint header-name sanitization bypassed via request trailers
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
Traefik is an open source HTTP reverse proxy and load balancer. From 3.2.0 until 3.7.13, Traefik entrypoint defenses aliasHeadersStrategy, underscoreHeadersStrategy, and forwardedHeaders inspect req.Header but not req.Trailer, allowing an unauthenticated client to submit an aliasing or trusted header name in an HTTP/1.1 chunked trailer or an HTTP/2 trailer. When the retry or buffering middleware reads the body before the reverse proxy clones the request, the attacker-controlled trailer value reaches a backend that merges trailers into the header namespace, bypassing the documented delete or reject behavior and potentially spoofing identity or forwarded routing data. This issue is fixed in 3.7.13.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| traefik | traefik | 3.2.0 to before 3.7.13 | 3.7.13 | Patch available | CNA |
| — | github.com/traefik/traefik/v3 (Go) | 3.2.0 to before 3.7.13 | 3.7.13 | Patch available | GHSA-v67p-phpq-fc8x |
- traefik Vendortraefik Affected 3.2.0 to before 3.7.13 Fixed in 3.7.13 Patch available CNA
- github.com/traefik/traefik/v3 (Go) Vendor— Affected 3.2.0 to before 3.7.13 Fixed in 3.7.13 Patch available GHSA-v67p-phpq-fc8x
Remediation
- Fix · CNA traefik (traefik) Fixed in 3.7.13
- Fix · GHSA-v67p-phpq-fc8x github.com/traefik/traefik/v3 (Go) Fixed in 3.7.13 Advisory →
Red Hat 1 advisory
- RHSA-2026:90321 Released 2026-10-26 · Red Hat rating CriticalRed Hat OpenShift Dev Spaces 3.31.0 Release.
- Red Hat OpenShift Dev Spaces 3.31 registry.redhat.io/devspaces/code-rhel9, registry.redhat.io/devspaces/dashboard-rhel9, registry.redhat.io/devspaces/jetbrains-ide-rhel9 +8
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift Dev Spaces 3.31 | Fixed | RHSA-2026:90321 |
Not affected: 1 product
- Red Hat OpenShift Dev Spaces 3.31
Timeline
- 2026-10-02 Threatist record created from CVE-2026-88004
- 2026-10-03 Alias added: GHSA-v67p-phpq-fc8x
- 2026-10-30 Fix available: RHSA-2026:90321 · Red Hat
- 2026-10-30 Fix available: Red Hat OpenShift Dev Spaces 3.31 · Red Hat
References
Patch 3
More Traefik vulnerabilities
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2023-25774 Uncontrolled Resource Consumption in Traefik CVSS 3.1HIGH 7.5
- TI-2025-40914 Traefik doesn't Prevent Path Normalization Bypass in Router + Middleware Rules CVSS 4.0MEDIUM 6.9
- TI-2022-07529 Authorization header displayed in the debug logs CVSS 3.1MEDIUM 6.5
- TI-2024-30459 HTTP client can remove the X-Forwarded headers in Traefik CVSS 3.1CRITICAL 9.8
- TI-2026-60261 Traefik v3.7.0 Authentication Bypass via from-to-www-redirect CVSS 4.0CRITICAL 9.3
Sources
- CVE-2026-88004 · CVE Program
- CVE-2026-88004 · NVD
- FIRST EPSS
- GHSA-v67p-phpq-fc8x · GitHub Advisory Database · CC BY 4.0
- CVE-2026-88004 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences