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CVE-2026-88008

9.1, critical

traefik HTTP Request Smuggling Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
9.1, critical critical CVSS v3.1
EPSS, next 30 days
0.5% higher than 40.4% of scored CVEs
Exploitation
No public evidence
Published
10 Sept 2026a month ago

Description

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.

Details

Vendor
Traefik
Product
traefik
Weakness
CWE-444 (opens in a new tab)
Status
Analyzed
Updated
14 Sept 2026
Assigner
security-advisories@github.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References 5

Patches and fixes 3

Other references 2

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Traefik CVEs

Every Traefik CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-88007 traefik Improper Authentication Vulnerability EPSS 0.6% 9.1, critical
  • CVE-2026-88879 Traefik is an HTTP reverse proxy and load balancer EPSS 0.3% 8.2, high
  • CVE-2026-88004 Traefik is an open source HTTP reverse proxy and load balancer EPSS 0.5% 7.4, high
  • CVE-2026-88009 traefik HTTP Request Smuggling Vulnerability EPSS 0.4% 8.2, high
  • CVE-2026-88011 Traefik is an open source HTTP reverse proxy and load balancer EPSS 0.4% 8.1, high
  • CVE-2026-85594 traefik Authorization Bypass Through User-Controlled Key Vulnerability EPSS 0.5% 9.8, critical
  • CVE-2026-85595 traefik Improper Authentication Vulnerability EPSS 0.7% 9.8, critical
  • CVE-2026-85596 traefik Improper Authentication Vulnerability EPSS 0.4% 9.8, critical

Beyond this page

Is CVE-2026-88008 in your network?

This page tells you how dangerous CVE-2026-88008 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-88008 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 16 Oct 2026, not the live upstream state.