Bug#1149909: logback: CVE-2026-104721

[Salvatore Bonaccorso]

Source: logback
Version: 1:1.6.3-2
X-Debbugs-CC: team at security.debian.org
Severity: important
Tags: security upstream

Hi,

The following vulnerability was published for logback.

CVE-2026-104721[0]:
| 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.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-104721
    https://www.cve.org/CVERecord?id=CVE-2026-104721
[1] https://logback.qos.ch/news.html#1.6.5

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore