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Fencer Vulns
high 8.7

CVE-2025-9648 json

Denial of Service in CivetWeb

published 2025-09-29 13 mo ago modified 2026-10-19 20 d ago also EUVD-2025-31569

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

Patch / fix

  • civetweb Debian 13 1.16+dfsg-2+deb13u1
  • civetweb Debian 14 1.16+dfsg-4

debian advisories DEBIAN-CVE-2025-9648

  • civetweb Ubuntu 24.04 LTS 1.16+dfsg-1ubuntu0.1
  • civetweb Ubuntu 26.04 LTS 1.16+dfsg-3ubuntu0.1
  • civetweb Ubuntu Pro 22.04 LTS 1.15+dfsg-3ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2025-9648

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ceph Azure Linux 3.0 18.2.2-11
  • ceph CBL-Mariner 2.0 16.2.10-10

azure linux advisories AZL-68073AZL-68085

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-9648 updated cvss 5.3

civetweb: Denial of Service in CivetWeb

  • Red Hat Advanced Cluster Security 4.7 advanced-cluster-security
    fixed: vendor fix RHSA-2025:23248
  • Red Hat Advanced Cluster Security 4.8 advanced-cluster-security
    fixed: vendor fix RHSA-2025:22179
  • Red Hat Advanced Cluster Security 4.9 advanced-cluster-security
    fixed: vendor fix RHSA-2025:21929
  • Red Hat Advanced Cluster Security 4 advanced-cluster-security/rhacs-collector-slim-rhel8 Red Hat Advanced Cluster Security 4.7 advanced-cluster-security Red Hat Advanced Cluster Security 4.8 advanced-cluster-security Red Hat Advanced Cluster Security 4.9 advanced-cluster-security
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
13 mo ago

Exploit prediction

0.76% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 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
CNA 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • CivetWeb CivetWeb

Classification

Weakness
  • CWE-158 Improper Neutralization of Null Byte or NUL Character

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.