{"id":"CVE-2026-93515","kind":"vulnerability","aliases":["CVE-2026-93515"],"related":[],"title":"X.org X Server: use-after-free lets a malicious X client crash or run code","description":"A use-after-free in present_clear_window_notifies()  in the X.org X Server before 21.1.25 and X Wayland before 24.1.14 could be used by malicious X clients to crash or potentially execute code in the X server context.","summary":"A use-after-free in present_clear_window_notifies() in the X.org X Server before 21.1.25 and X Wayland before 24.1.14 lets a malicious X client crash the server. The sources also say it could potentially execute code in the X server context.","severity":"medium","cvss":6.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["desktop","infrastructure","linux","x.org","x11","xorg","xwayland"],"not_affected_if":["no-untrusted-x-clients","wayland-only"],"how_to_check":"- `Xorg -version` or `X -version` to read the installed X.org X Server version\n- Check whether the X Wayland component (Xwayland) is installed and its version with `Xwayland -version`","fix":"- Upgrade the X.org X Server to `21.1.25` or later\n- Upgrade X Wayland (Xwayland) to `24.1.14` or later","status":"open","published_at":"2026-10-28T13:17:29+00:00","first_seen_at":"2026-10-28T13:33:01+00:00","triaged_at":"2026-10-28T13:34:17+00:00","updated_at":"2026-10-28T13:34:17+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-28T13:34:17Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade the X.org X Server to `21.1.25` or later\n- Upgrade X Wayland (Xwayland) to `24.1.14` or later","reach":"unknown","title":"X.org X Server: use-after-free lets a malicious X client crash or run code","impact":"medium","summary":"A use-after-free in present_clear_window_notifies() in the X.org X Server before 21.1.25 and X Wayland before 24.1.14 lets a malicious X client crash the server. The sources also say it could potentially execute code in the X server context.","category":"infrastructure","nicknames":[],"who_cares":["x.org","xorg","xwayland","linux","desktop","x11"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker crashes the X server or potentially runs code in it","analyst_note":"Check the upstream X.org advisory and NVD entry for the exact trigger conditions, whether a local-only X client suffices, and whether a remote attack path exists.","how_to_check":"- `Xorg -version` or `X -version` to read the installed X.org X Server version\n- Check whether the X Wayland component (Xwayland) is installed and its version with `Xwayland -version`","needs_analyst":true,"not_affected_if":["wayland-only","no-untrusted-x-clients"],"who_is_affected":"Systems running the X.org X Server before 21.1.25 or Xwayland before 24.1.14, where a local or remote X client can connect to the server. Systems that only run Wayland without Xwayland, or that do not accept X client connections from untrusted sources, are less exposed. The sources do not say which distributions or default configurations are affected.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000635,"input_tokens":3297,"output_tokens":610,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':18A,21A '-93515':19A,22A '21.1.25':46B,90C '24.1.14':51B,95C 'also':62B 'clear':37B,81C 'client':12A,56B,102C 'code':16A,68B,108C 'context':73B,113C 'could':65B,96C 'crash':13A,57B,104C 'cve':17A,20A 'desktop':23B 'execut':67B,107C 'free':7A,34B,78C 'infrastructur':24B 'let':8A,52B 'linux':25B 'malici':10A,54B,100C 'notifi':39B,83C 'potenti':66B,106C 'present':36B,80C 'run':15A 'say':63B 'server':3A,44B,59B,72B,88C,112C 'sourc':61B 'use':5A,32B,76C,98C 'use-after-fre':4A,31B,75C 'wayland':49B,93C 'window':38B,82C 'x':2A,11A,43B,48B,55B,71B,87C,92C,101C,111C 'x.org':1A,26B,42B,86C 'x11':27B 'xorg':28B 'xwayland':29B","nicknames":[],"mitigations":[],"who_affected":"Systems running the X.org X Server before 21.1.25 or Xwayland before 24.1.14, where a local or remote X client can connect to the server. Systems that only run Wayland without Xwayland, or that do not accept X client connections from untrusted sources, are less exposed. The sources do not say which distributions or default configurations are affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T13:17:29+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/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":"meissner@suse.de","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-93515","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93515","severity":null,"published_at":"2026-10-28T13:17:29+00:00","modified_at":"2026-10-28T13:17:29+00:00","first_seen_at":"2026-10-28T13:33:01+00:00","fetched_at":"2026-10-28T13:33:01+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}