CVE-2026-105244: medium-severity vulnerability in Apache log4net
Apache log4net: RemoteSyslogAppender silently deletes non-ASCII content
Published · Updated
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.3%
exploitation probability
0.3%top 75% of all CVEs
observed exploitation
nono source reports it
Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.
Every character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.
This issue affects Apache log4net: from 1.2.12 before 3.5.0.
Users are recommended to upgrade to version 3.5.0, which fixes the issue.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products
Apache Software Foundation · Apache log4netRelated CVEs — Apache log4net
In the same product, most dangerous first.
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