{"schema":"threatline.record/2","record":{"id":"CVE-2026-105243","aliases":[],"summary":"Apache log4net: Oversize EventLogAppender record silently discarded","details":"Insufficient Logging vulnerability in the EventLogAppender of Apache log4net.\n\nLong messages were truncated to a fixed size that exceeds what the Windows Event Log accepts once the log and source names are counted, and the event log then stored nothing and reported nothing. A party whose data reaches a log message could suppress the whole record by making it long enough. Only applications on Windows that use EventLogAppender 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.","categories":["Unclassified"],"product":"Apache log4net","vendor":"Apache Software Foundation","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-105243","source_modified_at":"2026-10-07T14:49:41.976Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"Apache log4net","vendor":"Apache Software Foundation","versions":[{"status":"affected","version":"1.2.9","lessThan":"3.5.0","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-105243","source_modified_at":"2026-10-07T14:49:41.976Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"Apache log4net","vendor":"Apache Software Foundation","versions":[{"status":"affected","version":"02e1e115435888485f2e28b414d267e39e799e07","lessThan":"28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed","versionType":"git"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-105243","source_modified_at":"2026-10-07T14:49:41.976Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"Apache log4net","ecosystem":null},"version":"3.5.0","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-105243","source_modified_at":"2026-10-07T14:49:41.976Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"Apache log4net","ecosystem":null},"version":"28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed","basis":"first unaffected version stated in the CVE record"}],"cvss":5.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00806,"percentile":0.56397,"score_date":"2026-10-23"},"published_at":"2026-10-06T19:51:25.116Z","modified_at":"2026-10-07T14:49:41.976Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-105243","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-07T14:49:41.976Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-105243","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/apache/logging-log4net/pull/315","tags":["patch"]},{"source":"CVE List","url":"https://github.com/apache/logging-log4net/commit/28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed","tags":["patch"]},{"source":"CVE List","url":"https://lists.apache.org/thread.html/jr6fj5skv1vnjbc9jmt8bp151p8ow1rp","tags":["vendor-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-10-07T14:49:30.641089Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-07T14:49:41.976Z","content_hash":"bc8282f8471191883d992209584f9fc0d984cdf51aedccc320bf03fe1cf4acee"}}