{"id":"CVE-2026-123785","kind":"vulnerability","aliases":["CVE-2026-123785"],"related":[],"title":"Fluxbox: crafted style values hang the window manager in an endless loop","description":"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.","summary":"Fluxbox, a Linux window manager, loops forever in its menu update code when a style file sets an oversized menu title height. An attacker who gets a crafted style loaded can hang the window manager and cause a denial of service at startup.","severity":"medium","cvss":6.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["fluxbox","linux-desktop","package","window-manager"],"not_affected_if":["default-style-only","other-window-manager"],"how_to_check":"- Run `fluxbox -version` or check the installed package version to see whether it is `1.3.7` or earlier\n- Look for a custom style file that sets `menu.titleHeight` to an unusually large value","fix":null,"status":"open","published_at":"2026-11-06T15:17:21+00:00","first_seen_at":"2026-11-06T15:42:44+00:00","triaged_at":"2026-11-06T15:44:27+00:00","updated_at":"2026-11-06T15:44:27+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-06T15:44:27Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Fluxbox: crafted style values hang the window manager in an endless loop","impact":"low","summary":"Fluxbox, a Linux window manager, loops forever in its menu update code when a style file sets an oversized menu title height. An attacker who gets a crafted style loaded can hang the window manager and cause a denial of service at startup.","audience":"businesses","category":"package","nicknames":[],"who_cares":["fluxbox","linux-desktop","window-manager"],"confidence":0.6,"fix_status":"unknown","needs_auth":"unknown","worst_case":"window manager hangs at startup, denying the user a usable desktop","analyst_note":"Confirm the fixed version and whether a patch exists; the NVD entry gives only the range through 1.3.7, and the VulnCheck advisory is linked but its content was not provided.","how_to_check":"- Run `fluxbox -version` or check the installed package version to see whether it is `1.3.7` or earlier\n- Look for a custom style file that sets `menu.titleHeight` to an unusually large value","plain_action":"","needs_analyst":true,"not_affected_if":["other-window-manager","default-style-only"],"who_is_affected":"Only systems running Fluxbox 1.3.7 or earlier where a style file with a very large menu title height is loaded. Exposure depends on whether untrusted or third-party style files are used; systems that use the default style from a trusted source or run other window managers can skip it.","user_interaction":"yes","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000702,"input_tokens":4294,"output_tokens":546,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-123785':15A,18A '-2026':14A,17A '1.3.7':72C 'allow':84C 'attack':50B,85C,96C 'caus':63B,112C 'code':38B 'column':108C 'contain':73C 'cpu':114C 'craft':2A,54B,92C 'cve':13A,16A 'denial':65B,117C 'desktop':22B 'endless':11A 'file':42B 'fluxbox':1A,19B,27B,70C 'forev':33B 'geometri':94C 'get':52B 'hang':5A,58B,87C 'height':48B 'infinit':75C 'linux':21B,29B 'linux-desktop':20B 'load':56B 'loop':12A,32B,76C,109C 'manag':8A,26B,31B,61B,90C 'menu':36B,46B,79C 'menu.titleheight':105C 'never':110C 'overs':45B,103C 'packag':23B 'servic':67B,119C 'set':43B 'src/fbtk/menu.cc':82C 'startup':69B,121C 'style':3A,41B,55B,93C,100C 'suppli':98C 'sustain':113C 'termin':111C 'titl':47B 'unbound':104C 'updat':37B 'updatemenu':80C 'use':115C 'valu':4A,95C 'via':91C 'vulner':77C 'window':7A,25B,30B,60B,89C 'window-manag':24B","nicknames":[],"mitigations":[],"who_affected":"Only systems running Fluxbox 1.3.7 or earlier where a style file with a very large menu title height is loaded. Exposure depends on whether untrusted or third-party style files are used; systems that use the default style from a trusted source or run other window managers can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["fluxbox","linuxdesktop","medium","package","windowmanager"],"campaign_type":null,"search_a":"'-123785':15A,18A '-2026':14A,17A 'craft':2A 'cve':13A,16A 'endless':11A 'fluxbox':1A 'hang':5A 'loop':12A 'manag':8A 'style':3A 'valu':4A 'window':7A","search_b":"'attack':50B 'caus':63B 'code':38B 'craft':54B 'denial':65B 'desktop':22B 'file':42B 'fluxbox':19B,27B 'forev':33B 'get':52B 'hang':58B 'height':48B 'linux':21B,29B 'linux-desktop':20B 'load':56B 'loop':32B 'manag':26B,31B,61B 'menu':36B,46B 'overs':45B 'packag':23B 'servic':67B 'set':43B 'startup':69B 'style':41B,55B 'titl':47B 'updat':37B 'window':25B,30B,60B 'window-manag':24B","search_c":"'1.3.7':72C 'allow':84C 'attack':85C,96C 'caus':112C 'column':108C 'contain':73C 'cpu':114C 'craft':92C 'denial':117C 'fluxbox':70C 'geometri':94C 'hang':87C 'infinit':75C 'loop':76C,109C 'manag':90C 'menu':79C 'menu.titleheight':105C 'never':110C 'overs':103C 'servic':119C 'src/fbtk/menu.cc':82C 'startup':121C 'style':93C,100C 'suppli':98C 'sustain':113C 'termin':111C 'unbound':104C 'updatemenu':80C 'use':115C 'valu':95C 'via':91C 'vulner':77C 'window':89C","first_public_at":"2026-11-06T15:17:21+00:00","kev":null,"cvss_vector":"CVSS: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_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-123785","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123785","severity":null,"published_at":"2026-11-06T15:17:21+00:00","modified_at":"2026-11-06T15:17:21+00:00","first_seen_at":"2026-11-06T15:42:44+00:00","fetched_at":"2026-11-06T15:42:44+00:00","note":null}],"documents":[{"id":87595,"url":"https://www.vulncheck.com/advisories/fluxbox-through-1.3.7-infinite-loop-via-menu-updatemenu-style-geometry","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}