CVE-2025-55753

Apache HTTP Server: mod_md (ACME), unintended retry intervals

Published Dec 5, 2025 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4452-1 apache2 security update
Ubuntu USN Ubuntu USN USN-7968-1 Apache HTTP Server vulnerabilities
Ubuntu USN Ubuntu USN USN-8338-1 Apache HTTP Server vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Apache
Apache http Server
Vendors & Products Apache
Apache http Server
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Apache HTTP Server: mod_md (ACME), unintended retry intervals
Weaknesses CWE-190
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apache
Published
Updated
Dec 5, 2025, 7:27 PM
Reserved
Aug 15, 2025, 8:38 AM
Status
Analyzed
Published
Dec 5, 2025, 11:15 AM
Modified
Oct 18, 2026, 3:10 PM
Severity
Important
Public date
Dec 5, 2025, 10:12 AM