CVE-2026-88011

HIGHNVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User while normalization-prone CGI, WSGI, PHP, and NGINX backends collapse both names. A backend can consequently consume the client value instead of the identity Traefik asserted, allowing identity spoofing for any header managed by Traefik. The aliasHeadersStrategy protection is disabled by default and must be configured as delete or reject. The mitigation is available in 2.11.56 and 3.7.12.

CVSS v3
8.1
EG Score
8.1(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity81% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

September 10, 2026

Last Modified

September 15, 2026

Advisory Details (5)

Auto-updated Sep 10, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

v3.7.12

Patch available: traefik/traefik v3.7.12

https://github.com/traefik/traefik/releases/tag/v3.7.12
github_release Patch Available

v2.11.56

Patch available: traefik/traefik v2.11.56

https://github.com/traefik/traefik/releases/tag/v2.11.56
github_commit

commit 0331801c7232 (traefik/traefik)

Fix landed in traefik/traefik commit 0331801c7232 — awaiting tagged release

https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbecf8
github_pr

Add an entry point option to handle request headers with aliasing names

Fix merged in traefik/traefik PR #13720 on 2026-08-24 — awaiting tagged release

https://github.com/traefik/traefik/pull/13720
github Patch Available🟡 PoC Available

ForwardAuth identity spoofing via dot-form header alias · Advisory · traefik/traefik · GitHub

https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8c

Vendor Advisories for CVE-2026-88011(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 1 ecosystem)
Go(2)
PackageVulnerable rangeFixed inDependents
github.com/traefik/traefik/v2—2.11.56—
github.com/traefik/traefik/v3—3.7.12—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 23× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 23:31 UTCEG score recompute
  2. 2026-09-19 00:25 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 01:20 UTCEG score recompute
  5. 2026-09-17 19:32 UTCEPSS rescore
  6. 2026-09-16 14:41 UTCEG score recompute
  7. 2026-09-16 14:09 UTCEPSS rescore
  8. 2026-09-16 05:15 UTCEPSS rescore
  9. 2026-09-15 15:02 UTCEG score recompute
  10. 2026-09-15 07:33 UTCEG score recompute
  11. 2026-09-15 03:12 UTCEPSS rescore
  12. 2026-09-14 20:00 UTCEG score recompute▲ 2.80
  13. 2026-09-14 19:59 UTCNVD updateCVSS v3 → 8.1 · severity → HIGH
  14. 2026-09-14 12:57 UTCEG score recompute
  15. 2026-09-13 16:48 UTCEPSS rescore
  16. 2026-09-12 16:26 UTCEG score recompute
  17. 2026-09-12 15:02 UTCEPSS rescore
  18. 2026-09-11 18:13 UTCEG score recompute
  19. 2026-09-11 14:53 UTCEPSS rescore
  20. 2026-09-11 14:53 UTCEPSS rescore
  21. 2026-09-10 16:20 UTCEG score recompute
  22. 2026-09-10 15:40 UTCEG score recompute
  23. 2026-09-10 15:39 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-88011?
CVE-2026-88011 is a high vulnerability published on September 10, 2026. Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User…
When was CVE-2026-88011 disclosed?
CVE-2026-88011 was first published in the National Vulnerability Database on September 10, 2026, with the most recent update on September 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-88011 actively exploited?
CVE-2026-88011 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 85.3% of all scored CVEs.
What is the CVSS score of CVE-2026-88011?
CVE-2026-88011 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-88011?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-88011, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-88011

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