GHSA-8g85-whqh-cr2f CVE-2023-47124 GO-2023-2381
Traefik vulnerable to potential DDoS via ACME HTTPChallenge
Medium
Go
- Severity
- 5.9 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.79%
- Chance of exploitation in the next 30 days. Higher than 56.30% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-400 Uncontrolled Resource Consumption
- CWE-772 Missing Release of Resource after Effective Lifetime
- Fix
- Available
- 2 packages have a fixed version
Description
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.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/traefik/traefik | all versions |
No fix yet |
| github.com/traefik/traefik/v2 | < 2.10.6 |
2.10.6 |
| github.com/traefik/traefik/v3 | < 3.0.0-beta5 |
3.0.0-beta5 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/traefik/traefik/v2 Go → 2.10.6
- go
go get github.com/traefik/traefik/v2@v2.10.6 && go mod tidy
github.com/traefik/traefik/v3 Go → 3.0.0-beta5
- go
go get github.com/traefik/traefik/v3@v3.0.0-beta5 && go mod tidy
Severity breakdown
CVSS 3.1 5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
CWE-772: Missing Release of Resource after Effective Lifetime
The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
How to prevent it
- Requirements: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.
- Implementation: It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free resources in a function. If you allocate resources that you intend to free upon completion of the function, you must be sure to free the resources at all exit points for that function including error conditions.
- Operation, Architecture and Design: Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
References
Advisories
Packages
Other links
- github.com/traefik/traefik/security/advisories/GHSA-8g85-whqh-cr2f
- doc.traefik.io/traefik/https/acme
- doc.traefik.io/traefik/https/acme
- doc.traefik.io/traefik/https/acme
- github.com/traefik/traefik/releases/tag/v2.10.6
- github.com/traefik/traefik/releases/tag/v3.0.0-beta5
- cloudflare.com/learning/ddos/ddos-attack-tools/slowloris
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GO-2026-6558 Traefik: BasicAuth singleflight coalescing reintroduces an unauthenticated username-enumeration timing oracle | Medium | Also affects github.com/traefik/traefik |
| GHSA-f52w-8j3h-j724 Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing path-scoped routing, middleware guards and access logging | High | Also affects github.com/traefik/traefik |
| GHSA-w4v4-9rw7-5326 Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization | Critical | Also affects github.com/traefik/traefik |
| GHSA-qqjf-53cj-pwvv Traefik HTTP/3 Backend NTLM Connection Reuse | Critical | Also affects github.com/traefik/traefik |
| GO-2026-6467 Traefik entrypoint header-name sanitization bypassed via request trailers | High | Also affects github.com/traefik/traefik |
| GHSA-rf44-j88r-hh8c Traefik: ForwardAuth identity spoofing via dot-form header alias | High | Also affects github.com/traefik/traefik |
| GHSA-7ghq-v6jf-g56c Traefik: respondingTimeouts.readTimeout is not applied to HTTP/3, leaving slow-body uploads unbounded | Medium | Also affects github.com/traefik/traefik |
| GHSA-62fc-8686-hfmq Traefik: `allowCrossNamespace=false` bypass via `@kubernetescrd` TraefikService backendRef | Medium | Also affects github.com/traefik/traefik |
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