CVE-2026-104721

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CVE-2026-104721
Path-traversal vulnerability in QOS.CH Sarl Logback-classic on Java (logback-classic module) allows path-traversal vulnerability. More specifically, an
MDC-based discriminator value flows unsanitized into a nested
FileAppender path, letting an attacker who influences that MDC value
(e.g. via an HTTP header)
create and append log files outside the intended directory.


This issue affects Logback-classic: from 0.9.14 through 1.6.4. This vulnerability is similar to CVE-2026-19880 but involves other attack techniques.