CVE-2025-53633 Chall-Manager's scenario decoding process does not check for zip bombs

What is CVE-2025-53633?

CVE-2025-53633 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. When decoding a scenario (i.e. a zip archive), the size of the decoded content is not checked, potentially leading to zip bombs decompression. 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 14042aa and shipped in v0.1.4.

Weakness: CWE-405

Which versions are affected by CVE-2025-53633?

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-2025-53633?

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-2025-53633 being exploited?

There is no known exploitation of CVE-2025-53633 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-2025-53634 Chall-Manager's HTTP Gateway have no header check timeout leading to potential slow loris attacks 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-r7fm-3pqm-ww5w, GO-2025-3810.