Bypassing IP allow-lists in traefik via HTTP/3 early data requests in QUIC 0-RTT handshakes

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2024-39321: 0.59% estimated exploitation activity in the next 30 days; percentile 48.43 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact There is a vulnerability in Traefik that allows bypassing IP allow-lists via HTTP/3 early data requests in QUIC 0-RTT handshakes sent with spoofed IP addresses. Patches - https://github.com/traefik/traefik/releases/tag/v2.11.6 - https://github.com/traefik/traefik/releases/tag/v3.0.4 - https://github.com/traefik/traefik/releases/tag/v3.1.0-rc3 Workarounds No workaround. For more information If you have any questions or comments about this advisory, please open an issue. <details <summaryOriginal Description</summary Summary Bypassing IP allow-lists in traefik via HTTP/3 early data requests in QUIC 0-RTT handshakes sent with spoofed IP addresses. Details HTTP/3 supports sending HTTP requests as early data during QUIC 0-RTT handshakes to reduce RTT overhead for connection resumptions. Early data is sent and received before the handshake is completed and the client's IP address is validated. The initial packet containing the QUIC 0-RTT handshake information and the early data HTTP…

Published by the source

5 Jul 2024, 20:13 UTC

Last modified by the source

8 Aug 2024, 05:06 UTC

Source last checked

26 Oct 2026, 15:04 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gxrv-wf35-62w9

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# Patch Next advisory brief: CVE-2024-39321

Advisory: Bypassing IP allow-lists in traefik via HTTP/3 early data requests in QUIC 0-RTT handshakes
IDs: CVE-2024-39321, GHSA-gxrv-wf35-62w9
Record: https://patchnext.com/advisories/cve-2024-39321 (revision 1, source checked 26 Oct 2026, 15:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/traefik/traefik/v3 3.1.0-rc3, 3.0.4; github.com/traefik/traefik/v2 2.11.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected >= 3.0.0-beta3, < 3.0.4; >= 3.1.0-rc1, < 3.1.0-rc3; fixed in 3.0.4, 3.1.0-rc3
- Go github.com/traefik/traefik/v2: affected < 2.11.6; fixed in 2.11.6

## 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.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## 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.
- 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://github.com/advisories/GHSA-gxrv-wf35-62w9 (GitHub-reviewed advisory GHSA-gxrv-wf35-62w9 lists affected ranges: Go github.com/traefik/traefik/v2 >=0 =3.0.0-beta3 =3.1.0-rc1 <3.1.0-rc3)

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