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

Quick assessment

Affected

fluxbox fluxbox

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Fluxbox 1.3.7 及更早版本中的函数存在操作系统命令注入漏洞。攻击者可通过精心构造的样式背景值执行任意命令。具体而言，攻击者可在背景 pixmap 路径、随机目录或渐变纹理文本中嵌入 Shell 元字符；当样式加载时，这些内容会被未转义地拼接，并通过调用命令执行，从而导致命令注入。

CVSS 7.8 · High Updated Nov 06, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

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Vulnerability Information

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Vulnerability Title

Fluxbox through 1.3.7 OS Command Injection via Style Background Values

Source: CVE Program / CVE List V5

Vulnerability 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.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Source: CVE Program / CVE List V5

Vulnerability Type

OS命令中使用的特殊元素转义处理不恰当(OS命令注入)

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
fluxbox	fluxbox	0 ~ 1.3.7	-

II. Public POCs for CVE-2026-123784

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-123784

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Other References for CVE-2026-123784 (5)

https://github.com/fluxbox/fluxbox product
https://github.com/fluxbox/fluxbox/pull/89 issue-tracking patch
https://github.com/fluxbox/fluxbox/commit/270bfbc28573037c9b8458488d193b219e33889f patch
https://github.com/fluxbox/fluxbox/blob/Release-1_3_7/src/RootTheme.cc#L192-L264 technical-description
https://www.vulncheck.com/advisories/fluxbox-through-1.3.7-os-command-injection-via-style-background-values third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-123784

IV. Related Vulnerabilities

Same product: fluxbox

CVE-2026-123785
Fluxbox through 1.3.7 Infinite Loop via Menu::updateMenu() S

Same vendor: fluxbox

CVE-2026-123785
Fluxbox through 1.3.7 Infinite Loop via Menu::updateMenu() S

Same weakness: CWE-78