{"id":"CVE-2026-107039","kind":"vulnerability","aliases":["CVE-2026-107039"],"related":[],"title":"NetGuard Android firewall: exported activity lets attackers force device reset","description":"Insecure permissions in the ActivityMain component of M66B/Marcel Bokhorst NetGuard no-root firewall versionCode 2026080101/versionName 2.337 allows unauthorized attackers to arbitrarily force a device reset or Denial of Service (DoS).","summary":"NetGuard, a no-root Android firewall app, has insecure permissions on its ActivityMain component in version 2.337 (versionCode 2026080101). The sources say an unauthorized attacker can force a device reset or denial of service.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["android","mobile","netguard","other"],"not_affected_if":["different-version","netguard-not-installed"],"how_to_check":"- Check the installed NetGuard version in the app's About screen or with `dumpsys package eu.faircode.netguard` on the device.\n- Confirm whether version `2.337` (versionCode `2026080101`) is installed.","fix":null,"status":"open","published_at":"2026-10-29T16:17:49+00:00","first_seen_at":"2026-10-29T16:25:55+00:00","triaged_at":"2026-10-29T16:32:19+00:00","updated_at":"2026-10-29T16:32:19+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-10-29T16:32:19Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"unknown","title":"NetGuard Android firewall: exported activity lets attackers force device reset","impact":"high","summary":"NetGuard, a no-root Android firewall app, has insecure permissions on its ActivityMain component in version 2.337 (versionCode 2026080101). The sources say an unauthorized attacker can force a device reset or denial of service.","audience":"everyone","category":"other","nicknames":[],"who_cares":["android","netguard","mobile"],"confidence":0.5,"fix_status":"unknown","needs_auth":"unknown","worst_case":"attacker forces device reset or denial of service","analyst_note":"Check the NVD entry and the NetGuard project for the exact trigger, whether a local app or remote party can invoke ActivityMain, and whether a fixed version was released.","how_to_check":"- Check the installed NetGuard version in the app's About screen or with `dumpsys package eu.faircode.netguard` on the device.\n- Confirm whether version `2.337` (versionCode `2026080101`) is installed.","plain_action":"If you use the NetGuard firewall app on Android, check its version and wait for or install a newer release from the developer.","needs_analyst":true,"not_affected_if":["netguard-not-installed","different-version"],"who_is_affected":"Android devices with the NetGuard no-root firewall app installed, specifically version 2.337 (versionCode 2026080101), where the ActivityMain component is reachable by other apps. The sources do not say whether a fixed version exists or whether the flaw needs a specific setting. Devices without NetGuard are not affected.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000709,"input_tokens":4121,"output_tokens":593,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-107039':13A,16A '-2026':12A,15A '2.337':37B,71C '2026080101':39B '2026080101/versionname':70C 'activ':5A 'activitymain':33B,59C 'allow':72C 'android':2A,17B,25B 'app':27B 'arbitrarili':76C 'attack':7A,45B,74C 'bokhorst':63C 'compon':34B,60C 'cve':11A,14A 'denial':52B,82C 'devic':9A,49B,79C 'dos':85C 'export':4A 'firewal':3A,26B,68C 'forc':8A,47B,77C 'insecur':29B,55C 'let':6A 'm66b/marcel':62C 'mobil':18B 'netguard':1A,19B,20B,64C 'no-root':22B,65C 'permiss':30B,56C 'reset':10A,50B,80C 'root':24B,67C 'say':42B 'servic':54B,84C 'sourc':41B 'unauthor':44B,73C 'version':36B 'versioncod':38B,69C","nicknames":[],"mitigations":[],"who_affected":"Android devices with the NetGuard no-root firewall app installed, specifically version 2.337 (versionCode 2026080101), where the ActivityMain component is reachable by other apps. The sources do not say whether a fixed version exists or whether the flaw needs a specific setting. Devices without NetGuard are not affected.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"everyone","plain_action":"If you use the NetGuard firewall app on Android, check its version and wait for or install a newer release from the developer.","first_public_at":"2026-10-29T16:17:49+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-107039","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107039","severity":null,"published_at":"2026-10-29T16:17:49+00:00","modified_at":"2026-10-29T16:17:49+00:00","first_seen_at":"2026-10-29T16:25:55+00:00","fetched_at":"2026-10-29T16:25:55+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"}