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CVE-2026-123785

Fluxbox through 1.3.7 Infinite Loop via Menu::updateMenu() Style Geometry

6.8 Medium

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.17%Scored on 2026-11-07. The trend appears after a second daily score.

What each source reports

CVE List Score used 6.8

Fluxbox through 1.3.7 Infinite Loop via Menu::updateMenu() Style Geometry

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Record
CVE-2026-123785
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-06
EUVDEUVD-2026-118303 6.8

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Record
EUVD-2026-118303
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-06
GitHub AdvisoriesGHSA-8g4r-mwj3-fw99 6.8

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk...

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Record
GHSA-8g4r-mwj3-fw99
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-06
NVD 6.8

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Record
CVE-2026-123785
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-06
OSV 6.8

Fluxbox through 1.3.7 Infinite Loop via Menu::updateMenu() Style Geometry

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Record
CVE-2026-123785
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-835
Updated
2026-11-08
OSVDEBIAN-CVE-2026-123785 6.8

Fluxbox through 1.3.7 contains an infinite loop vulnerability in Menu::updateMenu() in src/FbTk/Menu.cc that allows attackers to hang the window manager via crafted style geometry values. Attackers can supply a style with an oversized unbounded menu.titleHeight so the column loop never terminates, causing sustained CPU use and denial of service at startup.

Record
DEBIAN-CVE-2026-123785
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-07

Affected products

Affected packages

Affected packages
PackageAffectedFixed
fluxbox
Debian:12
 All versions, plus listed versions
1.3.5-2.11.3.6-1~exp11.3.7-11.3.7-1~exp1
 None known
fluxbox
Debian:13
 All versions, plus listed versions
1.3.7-1
 None known
fluxbox
Debian:14
 All versions, plus listed versions
1.3.7-1
 None known

History

History
RecordedChangedSources
referencesOSV
affected, aliases, referencesNVD, OSV
publishedCVE List, EUVD, NVD
publishedEUVD
references, severity, titleCVE List
aliases, products, published, referencesEUVD
first indexedGitHub Advisories

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-123785 is a medium vulnerability (CVSS 6.8) in Fluxbox, published November 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.17%, the 5th percentile. No source names a fixed version.

References

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