Bug 2547383

Summary: CVE-2026-105241 log4net: log4net: Log event suppression via improper Unicode handling in SmtpPickupDirAppender [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Vladimir Vasilev <vvasilev>
Component: log4netAssignee: Timotheus Pokorra <mailinglists>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: epel10CC: mailinglists, spotrh
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["d4af7a09-c3e9-43a3-866d-0ba770cb8e55"]}
Fixed In Version: Doc Type: ---
Doc Text:
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Clone Of: Environment:
Last Closed: 2026-10-07 16:58:11 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2547130    

Description Vladimir Vasilev 2026-10-07 10:41:37 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Improper Handling of Unicode Encoding vulnerability in the SmtpPickupDirAppender of Apache log4net.

Content that the mail file writer cannot encode, such as an unpaired UTF-16 surrogate, made the write throw. Every buffered event in the batch was discarded, not only the one carrying the content, and a truncated mail could be left in the pickup directory. A party whose data reaches a log message could suppress the records of other events. Only applications that use SmtpPickupDirAppender are affected.

This issue affects Apache log4net: from 1.2.9 before 3.5.0.

Users are recommended to upgrade to version 3.5.0, which fixes the issue.
Comment 1 Tom "spot" Callaway 2026-10-07 16:58:11 UTC 
log4net is not in EPEL 9 or EPEL 10.