CVE-2026-104721
Published:October 02, 2026
Updated:October 09, 2026
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.
Affected Packages
https://github.com/qos-ch/logback.git (GITHUB):
Affected version(s) >=v_1.6.0 <v_1.6.5Fix Suggestion:
Update to version v_1.6.5ch.qos.logback:logback-classic (JAVA):
Affected version(s) >=1.6.0 <1.6.5Fix Suggestion:
Update to version 1.6.5Related Resources (2)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
LOW
Weakness Type (CWE)
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
EPSS
Base Score:
0.33