CVE-2026-105241
mediumpriority · track · 0EPSS 0.008 · 57 %ileDEUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3772Apache log4net: Mehrere Schwachstellen ermöglichen Manipulation von DateienDeutsch2026-10-06csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Apache log4net ausnutzen, um Dateien zu manipulieren.
sources
Which sources assert this record, and when.
references (4) nvd
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2026/10/07/15Mailing ListThird Party Advisory
- https://github.com/apache/logging-log4net/commit/4d2e10f0908199604b4326f9df6d0b43b871e333Patch
- https://github.com/apache/logging-log4net/pull/315Patch
- https://lists.apache.org/thread.html/hg8dgh3oy8bp3dhb8nsygk9kw2o401wsMailing ListVendor Advisory
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