Skip to content
Patch Next
Sign inAdd to your agent

← Actionable
High, CVSS 7.0amended

Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization

CVE-2026-88008GHSA-w4v4-9rw7-5326

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Add to your agent

Affected packages

  • Go github.com/traefik/traefik/v3

    Affected
    >= 3.4.2, < 3.7.13
    Fixed in
    3.7.13

  • Go github.com/traefik/traefik/v2

    Affected
    >= 2.11.26, < 2.11.57
    Fixed in
    2.11.57

  • Go github.com/traefik/traefik

    Affected
    every version
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
7.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N · score source
EPSS
  • CVE-2026-88008: 0.49% estimated exploitation activity in the next 30 days; percentile 41.99 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary There is a high-severity request-smuggling vulnerability in Traefik's handling of the HTTP/1.1 Upgrade mechanism. Since Traefik moved to unencrypted HTTP/2 with prior knowledge (Go 1.24), a client-initiated Upgrade: h2c request header and its connection-specific HTTP2-Settings header were forwarded to the backend. A backend that honours the h2c upgrade and answers 101 Switching Protocols puts Traefik into a raw byte tunnel that bypasses the router and the entire middleware chain (authentication, IPAllowList, rate limiting) on a shared backend. The fix stops forwarding the Upgrade: h2c token and the HTTP2-Settings header; Upgrade: websocket is unaffected. Exploitation requires a backend that upgrades h2c without validating the Connection listing; common off-the-shelf servers were not exploitable in testing. Traefik v3.4.2 through v3.6 are end-of-life and are also affected; users on those versions must upgrade to v3.7.13. Patches -…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-w4v4-9rw7-5326

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GO-2026-6468

  4. Revision 1 · created ·

    Published from osv record GHSA-w4v4-9rw7-5326

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-88008

Advisory: Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization
IDs: CVE-2026-88008, GHSA-w4v4-9rw7-5326
Record: https://patchnext.com/advisories/cve-2026-88008 (revision 4, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/traefik/traefik/v3 3.7.13; github.com/traefik/traefik/v2 2.11.57. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected >= 3.4.2, < 3.7.13; fixed in 3.7.13
- Go github.com/traefik/traefik/v2: affected >= 2.11.26, < 2.11.57; fixed in 2.11.57
- Go github.com/traefik/traefik: affected every version

## Suggested inspection (read-only)
- Go github.com/traefik/traefik/v3: check the installed version with your package manager.
- Go github.com/traefik/traefik/v2: check the installed version with your package manager.
- Go github.com/traefik/traefik: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/traefik/traefik/v3, github.com/traefik/traefik/v2, github.com/traefik/traefik.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-w4v4-9rw7-5326 (OSV record GHSA-w4v4-9rw7-5326 lists affected ranges: Go github.com/traefik/traefik/v3 >=3.4.2 =2.11.26 <2.11.57 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6468 (OSV record GO-2026-6468 lists affected ranges: Go github.com/traefik/traefik >=0; Go github.com/traefik/traefik/v2 >=2.11.26 =3.4.2 <3.7.13 (fixed))
- Verified: https://github.com/advisories/GHSA-w4v4-9rw7-5326 (GitHub-reviewed advisory GHSA-w4v4-9rw7-5326 lists affected ranges: Go github.com/traefik/traefik/v3 >=3.4.2 =2.11.26 <2.11.57)

Commands are suggestions: review each one before running it.

Loading voting…