Fluxbox up to 1.3.7 RootTheme RootTheme::reconfigTheme os command injection

Summaryinfo

A vulnerability marked as problematic has been reported in Fluxbox up to 1.3.7. Impacted is the function RootTheme::reconfigTheme of the component RootTheme. This manipulation causes os command injection. This vulnerability appears as CVE-2026-123784. The attack requires local access. There is no available exploit.

Detailsinfo

A vulnerability was found in Fluxbox up to 1.3.7. It has been declared as problematic. Affected by this vulnerability is the function RootTheme::reconfigTheme of the component RootTheme. The manipulation with an unknown input leads to a os command injection vulnerability. The CWE definition for the vulnerability is CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-123784 since 11/06/2026. The exploitation appears to be easy. An attack has to be approached locally. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1202 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Fluxbox

Version

• 1.3.0
• 1.3.1
• 1.3.2
• 1.3.3
• 1.3.4
• 1.3.5
• 1.3.6
• 1.3.7

Website

• Product: https://github.com/fluxbox/fluxbox/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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