{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-105241","assignerOrgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","state":"PUBLISHED","assignerShortName":"apache","dateReserved":"2026-10-04T16:20:44.036Z","datePublished":"2026-10-06T19:49:03.994Z","dateUpdated":"2026-10-07T14:45:58.074Z"},"containers":{"cna":{"providerMetadata":{"orgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","shortName":"apache","dateUpdated":"2026-10-06T19:49:03.994Z"},"title":"Apache log4net: Unencodable content discards a whole SmtpPickupDirAppender batch","problemTypes":[{"descriptions":[{"description":"CWE-176 Improper Handling of Unicode Encoding","lang":"en","cweId":"CWE-176","type":"CWE"}]}],"source":{"discovery":"INTERNAL"},"affected":[{"vendor":"Apache Software Foundation","product":"Apache log4net","packageURL":"pkg:nuget/log4net","versions":[{"status":"affected","version":"1.2.9","lessThan":"3.5.0","versionType":"semver"}],"defaultStatus":"unaffected","collectionURL":"https://nuget.org/packages","packageName":"log4net"},{"vendor":"Apache Software Foundation","product":"Apache log4net","packageURL":"pkg:nuget/log4net","repo":"https://gitbox.apache.org/repos/asf/logging-log4net.git","versions":[{"status":"affected","version":"02e1e115435888485f2e28b414d267e39e799e07","lessThan":"4d2e10f0908199604b4326f9df6d0b43b871e333","versionType":"git"}],"defaultStatus":"unaffected","collectionURL":"https://nuget.org/packages","packageName":"log4net"}],"descriptions":[{"value":"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.","lang":"en","supportingMedia":[{"type":"text/html","base64":false,"value":"Improper Handling of Unicode Encoding vulnerability in the SmtpPickupDirAppender of Apache log4net.<br><br>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.<br><br>This issue affects Apache log4net: from 1.2.9 before 3.5.0.<br><br>Users are recommended to upgrade to version 3.5.0, which fixes the issue."}]}],"references":[{"url":"https://github.com/apache/logging-log4net/pull/315","tags":["patch"]},{"url":"https://github.com/apache/logging-log4net/commit/4d2e10f0908199604b4326f9df6d0b43b871e333","tags":["patch"]},{"url":"https://lists.apache.org/thread.html/hg8dgh3oy8bp3dhb8nsygk9kw2o401ws","tags":["vendor-advisory"]}],"metrics":[{"other":{"type":"Textual description of severity","content":{"text":"moderate"}},"scenarios":[{"lang":"en","value":"GENERAL"}]},{"scenarios":[{"lang":"en","value":"GENERAL"}],"format":"CVSS","cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE","baseSeverity":"MEDIUM","baseScore":5.3,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}}],"credits":[{"lang":"en","value":"The Apache Software Foundation","type":"finder"},{"lang":"en","value":"Claude Security","type":"tool"},{"lang":"en","value":"Jan Friedrich","type":"remediation developer"}],"x_generator":{"engine":"Vulnogram 1.0.3"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/10/07/15"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2026-10-07T06:11:57.596Z"}},{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-07T14:44:42.702949Z","id":"CVE-2026-105241","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-07T14:45:58.074Z"}}]}}