# CVE-2023-47124: Denial of service whith ACME HTTPChallenge in Traefik > Attackers can cause denial of service in Traefik via slowloris attacks when HTTPChallenge is used for ACME certificate renewal. - **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 4 Dec 2023 - **Updated:** 18 Dec 2024 - **Also known as:** ECHO-6d34-77d3-0a22, GHSA-8g85-whqh-cr2f, GO-2023-2381 ## What is CVE-2023-47124? CVE-2023-47124 is a medium-severity denial of service vulnerability in Traefik Traefik, published on 4 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description 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`. Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime) ## Which versions are affected by CVE-2023-47124? 7 open source packages ship an affected version, including github.com/traefik/traefik/v2, github.com/traefik/traefik and github.com/traefik/traefik/v3. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/traefik/traefik/v2` | Go | All versions | 2.10.6 | | `github.com/traefik/traefik/v2` | Go | All versions | 2.10.6 | | `github.com/traefik/traefik/v2` | Go | All versions | 2.10.6 | | `github.com/traefik/traefik` | Go | All versions | None | | `github.com/traefik/traefik/v3` | Go | All versions | 3.0.0-beta5 | | `github.com/traefik/traefik/v3` | Go | All versions | 3.0.0-beta5 | | `github.com/traefik/traefik/v3` | Go | All versions | 3.0.0-beta5 | Products: Traefik Traefik. ## How do I fix CVE-2023-47124? Upgrade github.com/traefik/traefik/v2 to 2.10.6 or later. ## Is CVE-2023-47124 being exploited? There is no known exploitation of CVE-2023-47124 in the wild and no public exploit code. ## Other vulnerabilities in Traefik Traefik - [CVE-2024-45410](https://insights.sbomify.com/CVE-2024-45410/): HTTP client can remove the X-Forwarded headers in Traefik (critical 9.8) - [CVE-2026-88877](https://insights.sbomify.com/CVE-2026-88877/): Traefik v3.7.0 Authentication Bypass via from-to-www-redirect (critical 9.3) - [CVE-2026-85595](https://insights.sbomify.com/CVE-2026-85595/): Traefik before v2.11.55 and v3.0.0 through v3.7.10 Authentication Bypass via digestAuth (critical 9.3) - [CVE-2026-88007](https://insights.sbomify.com/CVE-2026-88007/): Traefik HTTP/3 Backend NTLM Connection Reuse (critical 9.1) - [CVE-2026-88009](https://insights.sbomify.com/CVE-2026-88009/): Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing path-scoped routing, middleware guards and access logging (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2023-47124 and fix it if it is affected. What it is: CVE-2023-47124 is a medium-severity denial of service vulnerability in Traefik Traefik, published on 4 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2023-47124 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.10.6 - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.10.6 - github.com/traefik/traefik/v2 (Go): affected all versions; fixed in 2.10.6 - github.com/traefik/traefik (Go): affected all versions; no fix listed - github.com/traefik/traefik/v3 (Go): affected all versions; fixed in 3.0.0-beta5 - github.com/traefik/traefik/v3 (Go): affected all versions; fixed in 3.0.0-beta5 - github.com/traefik/traefik/v3 (Go): affected all versions; fixed in 3.0.0-beta5 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2023-47124/ (Markdown: https://insights.sbomify.com/CVE-2023-47124/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2023-47124 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-47124 - OSV: https://osv.dev/vulnerability/CVE-2023-47124 --- From sbomify Insights: https://insights.sbomify.com/CVE-2023-47124/ Summaries are generated and may contain mistakes; the official description above is the record.