{"schemaVersion":3,"id":"CVE-2026-105241","aliases":["UBUNTU-CVE-2026-105241","DEBIAN-CVE-2026-105241"],"status":"published","duplicateOf":null,"title":null,"description":"Improper Handling of Unicode Encoding vulnerability in the SmtpPickupDirAppender of Apache log4net.\n\nContent 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.\n\nThis issue affects Apache log4net: from 1.2.9 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","dates":{"published":"2026-10-06T19:49:03.994Z","modified":"2026-10-07T14:45:58.074Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · 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Handling of Unicode Encoding","description":"The product does not properly handle when an input contains Unicode encoding.","type":"weakness","status":"Draft","abstraction":"Variant","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/176.html"}],"affected":[{"vendor":"apache software foundation","product":"apache log4net","name":"Apache Log4net","label":"apache log4net","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 1.2.9, < 3.5.0","noFixRecorded":false,"fixedIn":null},{"text":"≥ 02e1e115435888485f2e28b414d267e39e799e07, < 4d2e10f0908199604b4326f9df6d0b43b871e333","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.2.9, < 3.5.0 | ≥ 02e1e115435888485f2e28b414d267e39e799e07, < 4d2e10f0908199604b4326f9df6d0b43b871e333","eol":null,"hubHref":"/vendor/apache_software_foundation/apache_log4net"},{"vendor":"apache","product":"log4net","name":"log4net","label":"log4net","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 1.2.9, < 3.5.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.2.9, < 3.5.0","eol":null,"hubHref":"/vendor/apache/log4net"},{"vendor":"debian","product":"log4net","name":"log4net","label":"log4net","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/log4net","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"log4net","name":"log4net","label":"log4net","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/log4net","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null}],"affectedCount":4,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/apache/logging-log4net/pull/315","label":"github.com/apache/logging-log4net/pull/315","hostname":"github.com","tags":["Patch","REPORT"]},{"url":"https://github.com/apache/logging-log4net/commit/4d2e10f0908199604b4326f9df6d0b43b871e333","label":"github.com/apache/logging-log4net/commit/4d2e10f0908199604b4326f9df6d0b43b871e333","hostname":"github.com","tags":["Patch"]},{"url":"https://lists.apache.org/thread.html/hg8dgh3oy8bp3dhb8nsygk9kw2o401ws","label":"lists.apache.org/thread.html/hg8dgh3oy8bp3dhb8nsygk9kw2o401ws","hostname":"lists.apache.org","tags":["Vendor Advisory","Mailing List"]},{"url":"http://www.openwall.com/lists/oss-security/2026/10/07/15","label":"www.openwall.com/lists/oss-security/2026/10/07/15","hostname":"www.openwall.com","tags":["Mailing List","Third Party Advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-105241","label":"ubuntu.com/security/CVE-2026-105241","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-105241","label":"www.cve.org/CVERecord?id=CVE-2026-105241","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://lists.apache.org/thread/hg8dgh3oy8bp3dhb8nsygk9kw2o401ws","label":"lists.apache.org/thread/hg8dgh3oy8bp3dhb8nsygk9kw2o401ws","hostname":"lists.apache.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-105241","label":"security-tracker.debian.org/tracker/CVE-2026-105241","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-06T19:49:03.994Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-07T14:45:58.074Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":21,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T18:18:11.808Z","stale":false,"partial":false}}