SB2026010537 - Red Hat Enterprise Linux 9 update for mod_md
Published: January 5, 2026
Security Bulletin ID
SB2026010537
Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Integer overflow (CVE-ID: CVE-2025-55753)
The vulnerability allows a remote attacker to perform a denial of service attack.
The vulnerability exists due to an integer overflow in mod_md (ACME) in the case of failed ACME certificate renewal. The web server will set the backoff timer becoming 0 after a number of failures (~30 days in default configurations), leading to a denial of service condition.
Remediation
Install update from vendor's website.