CVE-2026-88008

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 72% 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
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: 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. From 2.11.26 until 2.11.57 and 3.7.13, Traefik forwards a client-supplied Connection header requesting Upgrade, the Upgrade: h2c token, and HTTP2-Settings to a shared backend. If the backend accepts h2c and returns 101 Switching Protocols, Traefik enters a raw tunnel and no longer applies routers, BasicAuth, ForwardAuth, IPAllowList, RateLimit, access logging, metrics, or tracing to later HTTP/2 requests, allowing an unauthenticated request through an unprotected route to reach protected paths on the same backend. This issue is fixed in 2.11.57 and 3.7.13.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

September 10, 2026

Last Modified

September 14, 2026

Advisory Details (5)

Auto-updated Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available🟡 PoC Available

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization in github.com/traefik/traefik/v3 · Advisory · traefik/traefik · GitHub

https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326
github_release Patch Available

v3.7.13

Patch available: traefik/traefik v3.7.13

https://github.com/traefik/traefik/releases/tag/v3.7.13
github_release Patch Available

v2.11.57

Patch available: traefik/traefik v2.11.57

https://github.com/traefik/traefik/releases/tag/v2.11.57
github_pr

Do not forward h2c upgrade headers to the backend

Fix merged in traefik/traefik PR #13797 on 2026-08-28 — awaiting tagged release

https://github.com/traefik/traefik/pull/13797
github_commit

commit a277e94664ff (traefik/traefik)

Fix landed in traefik/traefik commit a277e94664ff — awaiting tagged release

https://github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3

Vendor Advisories for CVE-2026-88008(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—2.11.57—
github.com/traefik/traefik/v3—3.7.13—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 25× 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 17:18 UTCEG score recompute
  2. 2026-09-18 22:23 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 19:47 UTCEG score recompute
  5. 2026-09-17 19:32 UTCEPSS rescore
  6. 2026-09-16 18:09 UTCEG score recompute
  7. 2026-09-16 14:09 UTCEPSS rescore
  8. 2026-09-16 05:44 UTCEG score recompute
  9. 2026-09-16 05:15 UTCEPSS rescore
  10. 2026-09-15 03:30 UTCEG score recompute
  11. 2026-09-15 03:12 UTCEPSS rescore
  12. 2026-09-14 20:00 UTCEG score recompute▲ 2.10
  13. 2026-09-14 19:59 UTCNVD updateCVSS v3 → 9.1 · severity → CRITICAL
  14. 2026-09-14 02:01 UTCEG score recompute
  15. 2026-09-13 16:48 UTCEPSS rescore
  16. 2026-09-13 00:01 UTCEG score recompute
  17. 2026-09-12 15:02 UTCEPSS rescore
  18. 2026-09-11 21:59 UTCEG score recompute
  19. 2026-09-11 14:53 UTCEPSS rescore
  20. 2026-09-11 14:53 UTCEPSS rescore
  21. 2026-09-10 17:20 UTCEG score recompute
  22. 2026-09-10 17:00 UTCEG score recompute
  23. 2026-09-10 15:20 UTCEG score recompute
  24. 2026-09-10 15:00 UTCEG score recompute
  25. 2026-09-10 15:00 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-88008?
CVE-2026-88008 is a critical vulnerability published on September 10, 2026. Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.26 until 2.11.57 and 3.7.13, Traefik forwards a client-supplied Connection header requesting Upgrade, the Upgrade: h2c token, and HTTP2-Settings to a shared backend. If the backend accepts h2c and returns 101 Switching…
When was CVE-2026-88008 disclosed?
CVE-2026-88008 was first published in the National Vulnerability Database on September 10, 2026, with the most recent update on September 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-88008 actively exploited?
CVE-2026-88008 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 72.2% of all scored CVEs.
What is the CVSS score of CVE-2026-88008?
CVE-2026-88008 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-88008?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-88008, 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

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