CVE-2026-123784 Fluxbox through 1.3.7 OS Command Injection via Style Background Values

High 8.5 Published 6 Nov 2026 Updated 11 Nov 2026

Exploited in the wild: Not known
Fix: None listed

What is CVE-2026-123784?

CVE-2026-123784 is a high-severity vulnerability in fluxbox, published on 6 Nov 2026.

Official description

Fluxbox through 1.3.7 contains an OS command injection vulnerability in RootTheme::reconfigTheme() that allows attackers to execute commands via crafted style background values. Attackers can embed shell metacharacters in background pixmap paths, random directories, or gradient texture text, which are concatenated unescaped into an fbsetbg command run via $SHELL -c when the style loads.

Weakness: CWE-78

Which versions are affected by CVE-2026-123784?

How do I fix CVE-2026-123784?

No fix has been published for CVE-2026-123784 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-123784 being exploited?

There is no known exploitation of CVE-2026-123784 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-123784, GHSA-c5cr-c2wq-j45j, UBUNTU-CVE-2026-123784.