CVE-2025-55753

High

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.

SeverityHigh

CVSS7.5

Exploit probability—

Product

Apache Http Server

PublishedDec 5, 2025

First seenDec 5, 2025

Weakness typeCWE-190Integer overflow

How to fix

Update

apache http_server2.4.66 or later

Vendor advisories

httpd.apache.org/security/vulnerabilities_24.html

Affected products

Product	Affected versions	Fixed in
apache http_server	2.4.30 ≤ v < 2.4.66	2.4.66

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