CVE-2026-104721: Logback: Incomplete protection against CVE-2026-19880

Severity: medium (CVSS 6.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-02 · updated 2026-10-02
Weakness: CWE-22

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.

Affected products

QOS.CH Sarl Logback-classic: from 0.9.14 through 1.6.4

References

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

Get alerted when CVE-2026-104721 or the next vulnerability affects your stack