Security readout for executives and security teams
Plain-English summary
Traefik deployments using ForwardAuth can incorrectly trust a client-supplied forwarding prefix in a specific proxy configuration. An unauthenticated remote attacker may be able to bypass authentication and reach protected content. This matters most for internet-facing reverse proxy paths that depend on Traefik ForwardAuth for access control.
Executive priority
Prioritize remediation for internet-facing Traefik gateways that enforce authentication for business applications. The issue can undermine a central access-control layer, and patched versions are identified. Treat as high priority, especially for environments where Traefik protects sensitive internal or customer-facing services.
Technical view
CVE-2026-35051 affects Traefik before 2.11.43, 3.6.14, and 3.7.0-rc.2. With ForwardAuth, trustForwardHeader=false, and Traefik behind a trusted upstream proxy, spoofed X-Forwarded-Prefix handling can cause authentication bypass. CVSS is 8.2 high, with network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is likely where affected Traefik versions front protected routes, use ForwardAuth, set trustForwardHeader=false, and sit behind a trusted upstream proxy. Organizations using Traefik only without ForwardAuth, or on patched versions, are less likely to be exposed based on the supplied sources.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector indicates unauthenticated network exploitation with low complexity and no user interaction, so exposed edge deployments should be treated as urgent even without confirmed exploitation.
Researcher notes
The listed weaknesses are CWE-345 and CWE-501, pointing to improper source validation and trust-boundary confusion. Focus analysis on ForwardAuth request construction and forwarded-header normalization around X-Forwarded-Prefix. Avoid assuming exploit prevalence; the supplied sources only establish affected versions, conditions, severity, and fixed releases.
Mitigation direction
- Upgrade Traefik 2.x to 2.11.43 or later.
- Upgrade Traefik 3.6.x to 3.6.14 or later.
- Use 3.7.0-rc.2 or later for 3.7 release-candidate deployments.
- Check Red Hat advisory RHSA-2026:21772 for packaged remediation.
- Review vendor guidance before applying configuration workarounds.
Validation and detection
- Inventory all Traefik instances and record exact versions.
- Find routes using ForwardAuth middleware.
- Confirm whether trustForwardHeader=false is configured.
- Identify Traefik deployments behind trusted upstream proxies.
- Verify patched Traefik or vendor-fixed packages are deployed.
- Review access logs for unusual X-Forwarded-Prefix activity.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-345: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-501: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-35051 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N3.94.2redhat-SADPCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N——GitHub_MVulnerability scoring details
Base CVSS 4.0 score
7.8HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N
Base CVSS 3.1 score
8.2HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-04-30T21:01:28.437Z: Reported to Red Hat.
- 2026-04-30T20:26:06.716Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/traefik/traefik/security/advisories/GHSA-6384-m2mw-rf54CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/traefik/traefik/releases/tag/v2.11.43CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/traefik/traefik/releases/tag/v3.6.14CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2CVE reference, GitHub_M · x_refsource_MISC
- https://access.redhat.com/security/cve/CVE-2026-35051CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2464235CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35051.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:21772CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Insufficient Verification of Data Authenticity
Insufficient Verification of Data Authenticity represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Trust Boundary Violation
Trust Boundary Violation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.