Fluxbox through 1.3.7 OS Command Injection via Style Background Values
Fluxbox 1.3.7 and earlier are affected when a style with crafted background values is loaded. No fixed version is listed in the checked facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Fluxbox version 1.3.7 or earlier A style with crafted background values (pixmap paths, random directories, or gradient texture text) is loaded
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 14/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.5/10CVSS 8.5
- No patch0/5No signal
What would change the score
- Would score about 64 if added to CISA KEV
- Would score about 59 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Fluxbox version 1.3.7 or earlier A style with crafted background values (pixmap paths, random directories, or gradient texture text) is loadedApply the patch listed under Evidence.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- fluxbox fluxbox
through 1.3.7
Evidence 5
- Patch
- Patch
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123784
Is CVE-2026-123784 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Attackers can embed shell metacharacters in background pixmap paths, random directories, or gradient texture text in a style. Fluxbox then executes these as shell commands.Source: vulncheck.com
Which versions are affected by CVE-2026-123784?
fluxbox: through 1.3.7.Source: cve.now feed data
Am I affected, and how do I check?
Fluxbox version 1.3.7 or earlier is affected. The affected setup is a style with crafted background values being loaded. Check the installed Fluxbox version against 1.3.7 to see whether it falls in the range.Source: vulncheck.com
How do I fix CVE-2026-123784?
The checked facts name no fixed version, so no upgrade target can be given. Check the vendor's advisory for a fixed release before relying on any version.Source: vulncheck.com