{"id":"CVE-2026-109904","kind":"vulnerability","aliases":["CVE-2026-109904"],"related":[],"title":"X.Org Xwayland: integer overflow lets authenticated clients crash server or leak data","description":"A buffer overread caused by an integer-overflow in Proc/SProcXResQueryClientIds in X.Org xwayland before 24.1.15 and X Server before 21.1.26 could be used by attackers on authenticated X clients to crash the server or leak out information.","summary":"An integer overflow in the XRes extension's QueryClientIds handler causes a buffer overread in Xwayland before 24.1.15 and X Server before 21.1.26. An attacker with an authenticated X client can crash the server or leak memory contents.","severity":"medium","cvss":6.9,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"xwayland","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["infrastructure","linux","x-server","x.org","xwayland"],"not_affected_if":["no-authenticated-x-clients","patched-version"],"how_to_check":"- Check the installed Xwayland version with `Xwayland -version` and the X Server version with `Xorg -version`.\n- Confirm whether the XRes extension is loaded, which the sources do not say; unknown.","fix":"- Xwayland: move to `24.1.15` or later.\n- X Server: move to `21.1.26` or later.","status":"open","published_at":"2026-11-13T11:17:15+00:00","first_seen_at":"2026-11-13T11:44:16+00:00","triaged_at":"2026-11-13T11:44:32+00:00","updated_at":"2026-11-13T11:44:32+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-11-13T11:44:32Z","model":"claude-haiku-5-5","output":{"fix":"- Xwayland: move to `24.1.15` or later.\n- X Server: move to `21.1.26` or later.","reach":"local","title":"X.Org Xwayland: integer overflow lets authenticated clients crash server or leak data","impact":"medium","summary":"An integer overflow in the XRes extension's QueryClientIds handler causes a buffer overread in Xwayland before 24.1.15 and X Server before 21.1.26. An attacker with an authenticated X client can crash the server or leak memory contents.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["xwayland","x.org","linux","x-server"],"confidence":0.6,"fix_status":"available","needs_auth":"yes","worst_case":"Attacker crashes the X server or reads leaked memory contents","analyst_note":"Check the X.Org security advisory for the default configuration of the XRes extension and whether a fix for X Server 21.1.26 is listed; the NVD entry alone does not confirm it.","how_to_check":"- Check the installed Xwayland version with `Xwayland -version` and the X Server version with `Xorg -version`.\n- Confirm whether the XRes extension is loaded, which the sources do not say; unknown.","plain_action":"","product_name":"xwayland","needs_analyst":true,"not_affected_if":["patched-version","no-authenticated-x-clients"],"who_is_affected":"Systems running Xwayland before 24.1.15 or X Server before 21.1.26 where clients can authenticate to the X server. The sources do not say whether the XRes extension must be enabled by default, so whether a given install is reachable is unknown. Desktop users on current distributions with patched packages are not exposed.","user_interaction":"unknown","product_ecosystem":"vendor","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000777,"input_tokens":4556,"output_tokens":643,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-109904':15A,18A '-2026':14A,17A '21.1.26':49B,85C '24.1.15':44B,80C 'attack':51B,90C 'authent':6A,54B,92C 'buffer':39B,66C 'caus':37B,68C 'client':7A,56B,94C 'content':64B 'could':86C 'crash':8A,58B,96C 'cve':13A,16A 'data':12A 'extens':33B 'handler':36B 'inform':102C 'infrastructur':20B 'integ':3A,28B,72C 'integer-overflow':71C 'leak':11A,62B,100C 'let':5A 'linux':21B 'memori':63B 'overflow':4A,29B,73C 'overread':40B,67C 'proc/sprocxresqueryclientids':75C 'queryclientid':35B 'server':9A,24B,47B,60B,83C,98C 'use':88C 'x':23B,46B,55B,82C,93C 'x-server':22B 'x.org':1A,25B,77C 'xres':32B 'xwayland':2A,19A,26B,42B,78C","nicknames":[],"mitigations":[],"who_affected":"Systems running Xwayland before 24.1.15 or X Server before 21.1.26 where clients can authenticate to the X server. The sources do not say whether the XRes extension must be enabled by default, so whether a given install is reachable is unknown. Desktop users on current distributions with patched packages are not exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":["xwayland"],"ptokens":["xwayland"],"labels":["infrastructure","linux","medium","vendor","xorg","xserver","xwayland"],"campaign_type":null,"search_a":"'-109904':15A,18A '-2026':14A,17A 'authent':6A 'client':7A 'crash':8A 'cve':13A,16A 'data':12A 'integ':3A 'leak':11A 'let':5A 'overflow':4A 'server':9A 'x.org':1A 'xwayland':2A,19A","search_b":"'21.1.26':49B '24.1.15':44B 'attack':51B 'authent':54B 'buffer':39B 'caus':37B 'client':56B 'content':64B 'crash':58B 'extens':33B 'handler':36B 'infrastructur':20B 'integ':28B 'leak':62B 'linux':21B 'memori':63B 'overflow':29B 'overread':40B 'queryclientid':35B 'server':24B,47B,60B 'x':23B,46B,55B 'x-server':22B 'x.org':25B 'xres':32B 'xwayland':26B,42B","search_c":"'21.1.26':85C '24.1.15':80C 'attack':90C 'authent':92C 'buffer':66C 'caus':68C 'client':94C 'could':86C 'crash':96C 'inform':102C 'integ':72C 'integer-overflow':71C 'leak':100C 'overflow':73C 'overread':67C 'proc/sprocxresqueryclientids':75C 'server':83C,98C 'use':88C 'x':82C,93C 'x.org':77C 'xwayland':78C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-13T11:17:15+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/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":"meissner@suse.de","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-109904","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-109904","severity":null,"published_at":"2026-11-13T11:17:15+00:00","modified_at":"2026-11-13T11:17:15+00:00","first_seen_at":"2026-11-13T11:44:16+00:00","fetched_at":"2026-11-13T11:44:16+00:00","note":null}],"documents":[],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}