SB20260428218 - Improper Encoding or Escaping of Output in Apache log4cxx
Published: April 28, 2026
Security Bulletin ID
SB20260428218
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Improper Encoding or Escaping of Output (CVE-ID: CVE-2026-40023)
The vulnerability allows a remote attacker to suppress individual log records.
The vulnerability exists due to improper output neutralization in XMLLayout when processing logged data containing XML 1.0 forbidden characters. A remote attacker can inject crafted characters into log messages, NDC, or MDC property keys and values to suppress individual log records.
This can cause downstream log processing systems to reject invalid XML documents and fail to index affected records.
Remediation
Install update from vendor's website.