CVE-2025-55753

An integer overflow in the case of failed ACME certificate renewal leads, after a number of failures (~30 days in default configurations), to the backoff timer becoming 0. Attempts to renew the certificate then are repeated without delays until it succeeds.

This issue affects Apache HTTP Server: from 2.4.30 before 2.4.66.


Users are recommended to upgrade to version 2.4.66, which fixes the issue.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
apacheCNA
---
---
CVEADP
---
---
CISA-ADPADP
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 30%
VendorProductVersion
apachehttp_server
2.4.30 ≤
𝑥
< 2.4.66
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
apache2
bullseye
postponed
bullseye (security)
vulnerable
bookworm
2.4.66-1~deb12u1
fixed
bookworm (security)
vulnerable
trixie
2.4.66-1~deb13u1
fixed
forky
2.4.66-2
fixed
sid
2.4.66-2
fixed
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://httpd.apache.org/security/vulnerabilities_24.html
http://www.openwall.com/lists/oss-security/2025/12/04/4