CVE-2025-53634 — chall-manager
Fix: ctfer-io/chall-manager@1385bd8CVE-2025-53634 is a CWE-770 vulnerability in github.com/ctfer-io/chall-manager. A fix is available for github.com/ctfer-io/chall-manager — see the affected versions and patch details below.
Chall-Manager's HTTP Gateway have no header check timeout leading to potential slow loris attacks
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-53634.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
github.com/ctfer-io/chall-managerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ctfer-io/chall-manager | all versions | 0.1.4go get github.com/ctfer-io/chall-manager@v0.1.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ctfer-io/chall-manager, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/ctfer-io/chall-manager to 0.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-53634 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-53634 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-53634. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-53634 in your dependencies?
O3 Security finds CVE-2025-53634 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.