CVE-2025-55753

Publication date 5 December 2025

Last updated 19 January 2026

Ubuntu priority

Cvss 3 Severity Score

Description

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.

Why is this CVE low priority?

Apache developers have rated this as being low severity

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
apache2	25.10 questing	Fixed 2.4.64-1ubuntu3.2
	25.04 plucky	Ignored end of life, was needs-triage
	24.04 LTS noble	Fixed 2.4.58-1ubuntu8.10
	22.04 LTS jammy	Fixed 2.4.52-1ubuntu4.18
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Needs evaluation

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
apache2	Upstream: 20666cf Upstream: ab9dd8e Upstream: d2c5828

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	None
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

Related Ubuntu Security Notices (USN)

USN-7968-1
Apache HTTP Server vulnerabilities
19 January 2026