Description
Apache Log4net's XmlLayout https://logging.apache.org/log4net/manual/configuration/layouts.html#layout-list and XmlLayoutSchemaLog4J https://logging.apache.org/log4net/manual/configuration/layouts.html#layout-list , in versions before 3.3.0, fail to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets in MDC property keys and values, as well as the identity field that may carry attacker-influenced data. This causes an exception during serialization and the silent loss of the affected log event. An attacker who can influence any of these fields can exploit this to suppress individual log records, impairing audit trails and detection of malicious activity. Users are advised to upgrade to Apache Log4net 3.3.0, which fixes this issue.
INFO
Published Date :
2026-04-10T15:44:17.451Z
Last Modified :
2026-04-10T17:35:01.228Z
Source :
apache
AFFECTED PRODUCTS
The following products are affected by CVE-2026-40021 vulnerability.
| Vendors | Products |
|---|---|
| Apache |
|
REFERENCES
Here, you will find a curated list of external links that provide in-depth information to CVE-2026-40021.
