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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2025-9648?
How do I fix CVE-2025-9648?
Apply the vendor's patch.
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-2025-9648 being exploited?
There is no known exploitation of CVE-2025-9648 in the wild and no public exploit code.
Sources
Also known as AZL-68073, AZL-68085, DEBIAN-CVE-2025-9648, GHSA-2gxg-pvm2-2p6x, UBUNTU-CVE-2025-9648.