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

> An attacker can cause a Denial of Service via Slowloris attacks against Chall-Manager's HTTP Gateway due to missing header timeouts.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jul 2025
- **Updated:** 10 Jul 2025
- **Also known as:** GHSA-ggmv-j932-q89q, GO-2025-3809

## 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 (Allocation of Resources Without Limits or Throttling)

## 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.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/ctfer-io/chall-manager` | Go | All versions | 0.1.4 |
| `github.com/ctfer-io/chall-manager` | Go | All versions | 0.1.4 |
| `github.com/ctfer-io/chall-manager` | Go | All versions | 0.1.4 |

Products: Ctfer-Io Chall-Manager.

## How do I fix CVE-2025-53634?

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

## 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](https://insights.sbomify.com/CVE-2025-53632/): Chall-Manager's scenario decoding process does not check for zip slips (high 8.8)
- [CVE-2025-53633](https://insights.sbomify.com/CVE-2025-53633/): Chall-Manager's scenario decoding process does not check for zip bombs (high 8.7)
- [CVE-2026-32768](https://insights.sbomify.com/CVE-2026-32768/): Chall-Manager's invalid NetworkPolicy enables a malicious actor to pivot into another namespace (high 7.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-53634 and fix it if it is affected.

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

Affected packages and fixed versions:
- github.com/ctfer-io/chall-manager (Go): affected all versions; fixed in 0.1.4
- github.com/ctfer-io/chall-manager (Go): affected all versions; fixed in 0.1.4
- github.com/ctfer-io/chall-manager (Go): affected all versions; fixed in 0.1.4

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-2025-53634/ (Markdown: https://insights.sbomify.com/CVE-2025-53634/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-53634
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-53634
- OSV: https://osv.dev/vulnerability/CVE-2025-53634

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-53634/
Summaries are generated and may contain mistakes; the official description above is the record.