{"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": "2026-10-06T19:49:03.994Z"}, "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"}}}}

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{"affected": [{"affectedData": [{"collectionURL": "https://nuget.org/packages", "defaultStatus": "unaffected", "packageName": "log4net", "packageURL": "pkg:nuget/log4net", "product": "Apache log4net", "vendor": "Apache Software Foundation", "versions": [{"lessThan": "3.5.0", "status": "affected", "version": "1.2.9", "versionType": "semver"}]}, {"collectionURL": "https://nuget.org/packages", "defaultStatus": "unaffected", "packageName": "log4net", "packageURL": "pkg:nuget/log4net", "product": "Apache log4net", "repo": "https://gitbox.apache.org/repos/asf/logging-log4net.git", "vendor": "Apache Software Foundation", "versions": [{"lessThan": "4d2e10f0908199604b4326f9df6d0b43b871e333", "status": "affected", "version": "02e1e115435888485f2e28b414d267e39e799e07", "versionType": "git"}]}], "source": "security@apache.org"}], "cveTags": [], "descriptions": [{"lang": "en", "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."}], "id": "CVE-2026-105241", "lastModified": "2026-10-06T20:17:15.907", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "security@apache.org", "type": "Secondary"}]}, "published": "2026-10-06T20:17:15.907", "references": [{"source": "security@apache.org", "url": "https://github.com/apache/logging-log4net/commit/4d2e10f0908199604b4326f9df6d0b43b871e333"}, {"source": "security@apache.org", "url": "https://github.com/apache/logging-log4net/pull/315"}, {"source": "security@apache.org", "url": "https://lists.apache.org/thread.html/hg8dgh3oy8bp3dhb8nsygk9kw2o401ws"}], "sourceIdentifier": "security@apache.org", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-176"}], "source": "security@apache.org", "type": "Primary"}]}

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