{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-105240", "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "state": "PUBLISHED", "assignerShortName": "apache", "dateReserved": "2026-10-04T16:20:07.533Z", "datePublished": "2026-10-06T19:47:44.900Z", "dateUpdated": "2026-10-06T19:47:44.900Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "shortName": "apache", "dateUpdated": "2026-10-06T19:47:44.900Z"}, "title": "Apache log4net: NUL character truncates OutputDebugStringAppender records", "problemTypes": [{"descriptions": [{"description": "CWE-158 Improper Neutralization of Null Byte or NUL Character", "lang": "en", "cweId": "CWE-158", "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": "6046fe9d7f353b49fe995361c071ec2eea8f7ef6", "versionType": "git"}], "defaultStatus": "unaffected", "collectionURL": "https://nuget.org/packages", "packageName": "log4net"}], "descriptions": [{"value": "Improper Neutralization of Null Byte or NUL Character vulnerability in the OutputDebugStringAppender of Apache log4net.\n\nA NUL character in logged content ended the debug output record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently lost. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use OutputDebugStringAppender 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 Neutralization of Null Byte or NUL Character vulnerability in the OutputDebugStringAppender of Apache log4net.<br><br>A NUL character in logged content ended the debug output record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently lost. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use OutputDebugStringAppender 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/6046fe9d7f353b49fe995361c071ec2eea8f7ef6", "tags": ["patch"]}, {"url": "https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17", "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": "6046fe9d7f353b49fe995361c071ec2eea8f7ef6", "status": "affected", "version": "02e1e115435888485f2e28b414d267e39e799e07", "versionType": "git"}]}], "source": "security@apache.org"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper Neutralization of Null Byte or NUL Character vulnerability in the OutputDebugStringAppender of Apache log4net.\n\nA NUL character in logged content ended the debug output record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently lost. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use OutputDebugStringAppender 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-2026-105240", "lastModified": "2026-10-06T20:17:15.777", "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": "2026-10-06T20:17:15.777", "references": [{"source": "security@apache.org", "url": "https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6"}, {"source": "security@apache.org", "url": "https://github.com/apache/logging-log4net/pull/315"}, {"source": "security@apache.org", "url": "https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17"}], "sourceIdentifier": "security@apache.org", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-158"}], "source": "security@apache.org", "type": "Primary"}]}

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