Headline
CVE-2023-47124: Potential DDoS whith ACME HTTPChallenge
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.
Impact
There is a potential vulnerability in Traefik managing the ACME HTTP challenge.
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 (slowloris attack).
Patches
- https://github.com/traefik/traefik/releases/tag/v2.10.6
- https://github.com/traefik/traefik/releases/tag/v3.0.0-beta5
Workarounds
Replace the HTTPChallenge with the TLSChallenge or the DNSChallenge.
For more information
If you have any questions or comments about this advisory, please open an issue.
Related news
## Impact There is a potential vulnerability in Traefik managing the ACME HTTP challenge. When Traefik is configured to use the [HTTPChallenge](https://doc.traefik.io/traefik/https/acme/#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 ([slowloris attack](https://www.cloudflare.com/learning/ddos/ddos-attack-tools/slowloris/)). ## Patches - https://github.com/traefik/traefik/releases/tag/v2.10.6 - https://github.com/traefik/traefik/releases/tag/v3.0.0-beta5 ## Workarounds Replace the HTTPChallenge with the [TLSChallenge](https://doc.traefik.io/traefik/https/acme/#tlschallenge) or the [DNSChallenge](https://doc.traefik.io/traefik/https/acme/#dnschallenge). ## For more information If you have any questions or comments about this advisory, please [open an issue](https://github.com/traefik/traefik/issues).