{"id":"CVE-2026-105240","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-105240","generatedAt":"2026-10-28T07:05:13.308Z","title":"Improper Neutralization of Null Byte or NUL Character vulnerability in the OutputDebugStringAppender of Apache log4net.","description":"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.","published":"2026-10-06T20:17:16.000Z","lastModified":"2026-10-09T15:41:47.000Z","status":"Analyzed","sourceIdentifier":"security@apache.org","cvss":{"version":"3.1","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"},"cwe":["CWE-158"],"affected":["apache/log4net"],"epss":{"score":0.00807,"percentile":0.56638,"date":"2026-10-27","history":[{"date":"2026-10-07","score":0.00331,"percentile":0.24201}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.81%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-06T20:17:16.000Z","detail":{"score":"5.3","severity":"MEDIUM","publishedAt":"2026-10-06T20:17:15.777Z"},"summary":"New CVE, medium severity (CVSS 5.3)."}],"references":[{"url":"https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6","tags":["Patch"],"source":"security@apache.org"},{"url":"https://github.com/apache/logging-log4net/pull/315","tags":["Patch"],"source":"security@apache.org"},{"url":"https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17","tags":["Mailing List","Vendor Advisory"],"source":"security@apache.org"},{"url":"http://www.openwall.com/lists/oss-security/2026/10/07/18","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-105240","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}