CVE-2026-104721

Logback: Incomplete protection against CVE-2026-19880

State: Published
Severity: 6.3 Medium
Published: Oct 2, 2026
Updated: Oct 2, 2026
Reserved: Oct 2, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	6.3 Medium	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/S:P/AU:N/RE:M/U:Green	NCSC.ch

Weaknesses

CWE-22

Affected Products

Product	Versions
Logback-classicQOS.CH Sarl	0.9.14 through 1.6.4Affected 1.6.5Not affected

References

https://logback.qos.ch/news.html#1.6.5

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