Resource exhaustion in Ctfer-Io Chall-Manager

CVE-2025-53634

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.005 (42.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 42.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-53634: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-53634?
CVE-2025-53634 is a high-severity vulnerability in Ctfer-Io Chall-Manager, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2025-07-10.
How severe is CVE-2025-53634?
High severity. CVSS v3 base score is 7.5 out of 10.