CVE-2025-53634 Chall-Manager's HTTP Gateway have no header check timeout leading to potential slow loris attacks

What is CVE-2025-53634?

CVE-2025-53634 is a high-severity denial of service vulnerability in ctfer-io chall-manager, published on 10 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Chall-Manager is a platform-agnostic system able to start Challenges on Demand of a player. The HTTP Gateway processes headers, but with no timeout set. With a slow loris attack, an attacker could cause Denial of Service (DoS). Exploitation does not require authentication nor authorization, so anyone can exploit it. It should nonetheless not be exploitable as it is highly recommended to bury Chall-Manager deep within the infrastructure due to its large capabilities, so no users could reach the system. Patch has been implemented by commit 1385bd8 and shipped in v0.1.4.

Weakness: CWE-770

Which versions are affected by CVE-2025-53634?

3 open source packages ship an affected version, including github.com/ctfer-io/chall-manager. It affects 1 product.

Products include Ctfer-Io Chall-Manager.

How do I fix CVE-2025-53634?

Upgrade github.com/ctfer-io/chall-manager to 0.1.4 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-53634 being exploited?

There is no known exploitation of CVE-2025-53634 in the wild and no public exploit code.

Other vulnerabilities in ctfer-io chall-manager

• CVE-2025-53632 Chall-Manager's scenario decoding process does not check for zip slips High 8.8
• CVE-2025-53633 Chall-Manager's scenario decoding process does not check for zip bombs High 8.7
• CVE-2026-32768 Chall-Manager's invalid NetworkPolicy enables a malicious actor to pivot into another namespace High 7.9

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-ggmv-j932-q89q, GO-2025-3809.