CVE-2025-55753: http server Integer Overflow — Fix

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Weakness Type (CWE)

CWE-190 Integer Overflow

Affected Products

Vendor	Product	Versions
apache	http_server	2.4.30 — 2.4.66

References

Advisories & Patches

https://httpd.apache.org/security/vulnerabilities_24.html

Other References

http://www.openwall.com/lists/oss-security/2025/12/04/4

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-55753? +

CVE-2025-55753 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-55753? +

CVE-2025-55753 affects products from apache, specifically: http_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-55753? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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