{"schemaVersion":3,"id":"CVE-2026-105242","aliases":["UBUNTU-CVE-2026-105242","DEBIAN-CVE-2026-105242"],"status":"published","duplicateOf":null,"title":null,"description":"Improper Handling of Exceptional Conditions vulnerability in the aspnet-request pattern converter of Apache log4net.\n\nReading request parameters triggers ASP.NET request validation, so a request carrying content such as markup made the layout throw and the appender discarded the whole event. A sender could suppress the log record of their own request. Only applications on ASP.NET for .NET Framework whose layout uses %aspnet-request are affected.\n\nThis issue affects Apache log4net: from 1.2.11 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","dates":{"published":"2026-10-06T19:50:19.075Z","modified":"2026-10-07T14:49:06.441Z","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 · Ubuntu","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":10,"impact":2.3,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · 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Handling of Exceptional Conditions","description":"The product does not handle or incorrectly handles an exceptional condition.","type":"weakness","status":"Incomplete","abstraction":"Class","likelihoodOfExploit":"Medium","url":"https://cwe.mitre.org/data/definitions/755.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":"≥ 1.2.11, < 3.5.0","noFixRecorded":false,"fixedIn":null},{"text":"≥ 243f1e9f3ee235955bade4b4fe664a903378719a, < 145203420c579a703008b4b723b6a080757f4964","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.2.11, < 3.5.0 | ≥ 243f1e9f3ee235955bade4b4fe664a903378719a, < 145203420c579a703008b4b723b6a080757f4964","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":"≥ 1.2.11, < 3.5.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.2.11, < 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/316","label":"github.com/apache/logging-log4net/pull/316","hostname":"github.com","tags":["Patch","REPORT"]},{"url":"https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964","label":"github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964","hostname":"github.com","tags":["Patch"]},{"url":"https://lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx","label":"lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx","hostname":"lists.apache.org","tags":["Vendor Advisory","Mailing List"]},{"url":"http://www.openwall.com/lists/oss-security/2026/10/07/16","label":"www.openwall.com/lists/oss-security/2026/10/07/16","hostname":"www.openwall.com","tags":["Mailing List","Third Party Advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-105242","label":"ubuntu.com/security/CVE-2026-105242","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-105242","label":"www.cve.org/CVERecord?id=CVE-2026-105242","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://lists.apache.org/thread/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx","label":"lists.apache.org/thread/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx","hostname":"lists.apache.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-105242","label":"security-tracker.debian.org/tracker/CVE-2026-105242","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-06T19:50:19.075Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-07T14:49:06.441Z","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":"2026-10-20T19:19:09.747Z","stale":false,"partial":false}}