{"id":"CVE-2026-105244","aliases":["DEBIAN-CVE-2026-105244","EUVD-2026-93870","GHSA-g956-ph29-3vq5","UBUNTU-CVE-2026-105244"],"status":"published","title":"Apache log4net: RemoteSyslogAppender silently deletes non-ASCII content","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00823,"percentile":0.57834,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-116"],"published":"2026-10-06T19:52:31Z","modified":"2026-10-28T02:30:33Z","affected":[{"source":"osv","ecosystem":"Debian:13","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-10","1.2.10+dfsg-9"]},{"source":"osv","ecosystem":"Debian:14","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-10","1.2.10+dfsg-9"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-6","1.2.10+dfsg-7","1.2.10+dfsg-7ubuntu0.16.04.1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-7","1.2.10+dfsg-7ubuntu0.18.04.1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-7","1.2.10+dfsg-7ubuntu0.20.04.1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-8"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-8","1.2.10+dfsg-9"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-9build1","1.2.10+dfsg-10"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"log4net","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.10+dfsg-9","1.2.10+dfsg-9build1"]}],"products":[{"vendor":"apache","product":"log4net"},{"vendor":"apache software foundation","product":"apache log4net"}],"references":[{"url":"https://github.com/apache/logging-log4net/pull/315","tags":["patch","Patch","Vendor Advisory","fix","report"]},{"url":"https://github.com/apache/logging-log4net/commit/77717061b20d4346b6c0ce6b54643d85fb348bc7","tags":["patch","Patch","fix"]},{"url":"https://lists.apache.org/thread.html/q7649hhdodthoqw8jsjgtnb4m8qfy6d6","tags":["vendor-advisory","Mailing List","Vendor Advisory","advisory"]},{"url":"http://www.openwall.com/lists/oss-security/2026/10/07/19","tags":["Mailing List","Third Party Advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-105244","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-g956-ph29-3vq5"},{"url":"https://nuget.org/packages","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/105xxx/CVE-2026-105244.json","tags":["advisory"]},{"url":"https://gitbox.apache.org/repos/asf/logging-log4net.git","tags":["package"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-105244","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-105244","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-105244","tags":["report"]},{"url":"https://lists.apache.org/thread/q7649hhdodthoqw8jsjgtnb4m8qfy6d6","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-105244","title":"Apache log4net: RemoteSyslogAppender silently deletes non-ASCII content","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T19:52:31.116Z","modified":"2026-10-07T14:50:49.648Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-116"],"updated_at":"2026-11-02T14:19:56.755658Z"}],"euvd":[{"id":"EUVD-2026-93870","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T19:52:31Z","modified":"2026-10-07T14:50:49Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T17:27:35.164729Z"}],"ghsa":[{"id":"GHSA-g956-ph29-3vq5","title":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache...","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T21:31:59Z","modified":"2026-10-07T09:32:19Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-116"],"updated_at":"2026-11-02T15:12:53.496212Z"}],"nvd":[{"id":"CVE-2026-105244","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T20:17:16.297Z","modified":"2026-10-09T15:18:44.677Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-116"],"updated_at":"2026-11-02T14:12:54.809359Z"}],"osv":[{"id":"CVE-2026-105244","title":"Apache log4net: RemoteSyslogAppender silently deletes non-ASCII content","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T19:52:31.116Z","modified":"2026-10-28T02:30:33.59469948Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-116"],"updated_at":"2026-11-02T15:44:54.583213Z"},{"id":"DEBIAN-CVE-2026-105244","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.  Every character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.  This issue affects Apache log4net: from 1.2.12 before 3.5.0.  Users are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T20:17:16.297Z","modified":"2026-10-08T09:47:25.921258904Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:48.903138Z"},{"id":"UBUNTU-CVE-2026-105244","description":"Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net. Every character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected. This issue affects Apache log4net: from 1.2.12 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.","status":"published","published":"2026-10-06T20:17:00Z","modified":"2026-10-17T12:58:44.132631249Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T16:55:59.130573Z"}]}}