# CVE-2025-9648: Denial of Service in CivetWeb

> Remote attackers can cause denial of service in CivetWeb library via crafted HTTP POST requests triggering an infinite loop.

- **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:** 29 Sep 2025
- **Updated:** 29 Sep 2025
- **Also known as:** AZL-68073, AZL-68085, DEBIAN-CVE-2025-9648, GHSA-2gxg-pvm2-2p6x, UBUNTU-CVE-2025-9648

## What is CVE-2025-9648?

CVE-2025-9648 is a high-severity denial of service vulnerability in CivetWeb, published on 29 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial of service (DoS) condition. By sending a specially crafted HTTP POST request containing a null byte in the payload, the server enters an infinite loop during form data parsing. Multiple malicious requests will result in complete CPU exhaustion and render the service unresponsive to further requests.

This issue was fixed in commit 782e189. This issue affects only the library, standalone executable pre-built by vendor is not affected.

Weakness: CWE-158 (Improper Neutralization of Null Byte or NUL Character)

## Which versions are affected by CVE-2025-9648?


## How do I fix CVE-2025-9648?

Apply the vendor's patch.

## Is CVE-2025-9648 being exploited?

There is no known exploitation of CVE-2025-9648 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-9648 and fix it if it is affected.

What it is: CVE-2025-9648 is a high-severity denial of service vulnerability in CivetWeb, published on 29 Sep 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-2025-9648 in the wild and no public exploit code.

Affected product: CivetWeb. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2025-9648/ (Markdown: https://insights.sbomify.com/CVE-2025-9648/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-9648
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-9648
- OSV: https://osv.dev/vulnerability/CVE-2025-9648

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-9648/
Summaries are generated and may contain mistakes; the official description above is the record.