Denial of service whith ACME HTTPChallenge in Traefik
Priority LOW 28CWE-772Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-772.
Summary
Traefik is an open source HTTP reverse proxy and load balancer. When Traefik is configured to use the `HTTPChallenge` to generate and renew the Let's Encrypt TLS certificates, the delay authorized to solve the challenge (50 seconds) can be exploited by attackers to achieve a `slowloris attack`. This vulnerability has been patch in version 2.10.6 and 3.0.0-beta5. Users are advised to upgrade. Users unable to upgrade should replace the `HTTPChallenge` with the `TLSChallenge` or the `DNSChallenge`.
Why it matters now
EPSS 0.00791 56th percentileScored 2026-11-07
Fix Fixed traefik (traefik): 2.10.6, 3.0.0-beta5github.com/traefik/traefik/v2 (Go): 2.10.6+1 more product
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| traefik | traefik | before 2.10.6; 3.0.0-beta1 to before 3.0.0-beta5 | 2.10.6, 3.0.0-beta5 | Patch available | CNA |
| — | github.com/traefik/traefik/v2 (Go) | before 2.10.6 | 2.10.6 | Patch available | GHSA-8g85-whqh-cr2f |
| — | github.com/traefik/traefik/v3 (Go) | before 3.0.0-beta5 | 3.0.0-beta5 | Patch available | GHSA-8g85-whqh-cr2f |
- traefik Vendortraefik Affected before 2.10.6; 3.0.0-beta1 to before 3.0.0-beta5 Fixed in 2.10.6, 3.0.0-beta5 Patch available CNA
- github.com/traefik/traefik/v2 (Go) Vendor— Affected before 2.10.6 Fixed in 2.10.6 Patch available GHSA-8g85-whqh-cr2f
- github.com/traefik/traefik/v3 (Go) Vendor— Affected before 3.0.0-beta5 Fixed in 3.0.0-beta5 Patch available GHSA-8g85-whqh-cr2f
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* | up to 2.10.5 | Vulnerable | traefik |
| cpe:2.3:a:traefik:traefik:3.0.0:beta1:*:*:*:*:*:* | 3.0.0 beta1 | Vulnerable | traefik |
| cpe:2.3:a:traefik:traefik:3.0.0:beta2:*:*:*:*:*:* | 3.0.0 beta2 | Vulnerable | traefik |
| cpe:2.3:a:traefik:traefik:3.0.0:beta3:*:*:*:*:*:* | 3.0.0 beta3 | Vulnerable | traefik |
| cpe:2.3:a:traefik:traefik:3.0.0:beta4:*:*:*:*:*:* | 3.0.0 beta4 | Vulnerable | traefik |
- cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* Versions up to 2.10.5 Vulnerable ·traefik
- cpe:2.3:a:traefik:traefik:3.0.0:beta1:*:*:*:*:*:* Versions 3.0.0 beta1 Vulnerable ·traefik
- cpe:2.3:a:traefik:traefik:3.0.0:beta2:*:*:*:*:*:* Versions 3.0.0 beta2 Vulnerable ·traefik
- cpe:2.3:a:traefik:traefik:3.0.0:beta3:*:*:*:*:*:* Versions 3.0.0 beta3 Vulnerable ·traefik
- cpe:2.3:a:traefik:traefik:3.0.0:beta4:*:*:*:*:*:* Versions 3.0.0 beta4 Vulnerable ·traefik
Remediation
- Fix · CNA traefik (traefik) Fixed in 2.10.6, 3.0.0-beta5
- Fix · GHSA-8g85-whqh-cr2f github.com/traefik/traefik/v2 (Go) Fixed in 2.10.6 Advisory →
- Fix · GHSA-8g85-whqh-cr2f github.com/traefik/traefik/v3 (Go) Fixed in 3.0.0-beta5 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2023-47124
- 2026-10-03 Alias added: GHSA-8g85-whqh-cr2f
References
Advisory 2
Other 7
- https://doc.traefik.io/traefik/https/acme/#dnschallenge
- https://doc.traefik.io/traefik/https/acme/#httpchallenge
- https://doc.traefik.io/traefik/https/acme/#tlschallenge
- https://github.com/traefik/traefik/releases/tag/v2.10.6
- https://github.com/traefik/traefik/releases/tag/v3.0.0-beta5
- https://www.cloudflare.com/learning/ddos/ddos-attack-tools/slowloris
- https://github.com/traefik/traefik
More Traefik vulnerabilities
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2023-25774 Uncontrolled Resource Consumption in Traefik CVSS 3.1HIGH 7.5
- TI-2025-40914 Traefik doesn't Prevent Path Normalization Bypass in Router + Middleware Rules CVSS 4.0MEDIUM 6.9
- TI-2022-07529 Authorization header displayed in the debug logs CVSS 3.1MEDIUM 6.5
- TI-2024-30459 HTTP client can remove the X-Forwarded headers in Traefik CVSS 3.1CRITICAL 9.8
- TI-2026-60261 Traefik v3.7.0 Authentication Bypass via from-to-www-redirect CVSS 4.0CRITICAL 9.3
Sources
- CVE-2023-47124 · CVE Program
- CVE-2023-47124 · NVD
- FIRST EPSS
- GHSA-8g85-whqh-cr2f · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences