{"id":"CVE-2026-97371","kind":"vulnerability","aliases":["CVE-2026-97371"],"related":[],"title":"ntopng: custom-category packet matching corrupts the stack, crashing the monitor","description":"ntopng is a web-based network traffic monitoring application. Prior to 6.7.260721, ndpi_get_custom_category_match writes a four-byte nDPI protocol-category value through a pointer to the two-byte id variable in IpAddress::reloadBlacklist in src/IpAddress.cpp during packet dissection and host initialization. A remote unauthenticated attacker on a monitored network segment can send packets that match custom-category rules, causing stack corruption and denial of service without user interaction. This issue is fixed in version 6.7.260721.","summary":"ntopng writes a four-byte protocol-category value into a two-byte variable on the stack when it dissects packets that match custom-category rules. A remote, unauthenticated attacker on a monitored network segment can send such packets and corrupt the stack, causing a denial of service.","severity":"medium","cvss":5.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["network-monitoring","ntopng","package","self-hosted"],"not_affected_if":["fixed-version","no-custom-categories"],"how_to_check":"- Check the installed ntopng version with `ntopng --version` and compare it with the fixed version below.\n- Check whether custom categories are configured in ntopng, since only packets matching those rules reach the flawed code path.","fix":"- ntopng: `6.7.260721`","status":"open","published_at":"2026-11-05T17:18:22+00:00","first_seen_at":"2026-11-05T17:40:05+00:00","triaged_at":"2026-11-05T17:42:37+00:00","updated_at":"2026-11-05T17:42:37+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-05T17:42:37Z","model":"claude-haiku-5-5","output":{"fix":"- ntopng: `6.7.260721`","reach":"network","title":"ntopng: custom-category packet matching corrupts the stack, crashing the monitor","impact":"low","summary":"ntopng writes a four-byte protocol-category value into a two-byte variable on the stack when it dissects packets that match custom-category rules. A remote, unauthenticated attacker on a monitored network segment can send such packets and corrupt the stack, causing a denial of service.","audience":"businesses","category":"package","nicknames":[],"who_cares":["ntopng","self-hosted","network-monitoring"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"ntopng process crashes, causing denial of service on monitoring","analyst_note":"","how_to_check":"- Check the installed ntopng version with `ntopng --version` and compare it with the fixed version below.\n- Check whether custom categories are configured in ntopng, since only packets matching those rules reach the flawed code path.","plain_action":"","needs_analyst":false,"not_affected_if":["fixed-version","no-custom-categories"],"who_is_affected":"Teams running ntopng to monitor network traffic, especially where a monitored segment can be reached by untrusted hosts. The flaw is reached during packet dissection and host initialization, and only packets matching custom-category rules trigger the bad write, so deployments without custom categories are less exposed. Teams on ntopng 6.7.260721 or later are not affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000705,"input_tokens":4316,"output_tokens":546,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-97371':15A,18A '6.7.260721':90C,161C 'applic':87C 'attack':59B,130C 'base':83C 'byte':32B,41B,100C,113C 'categori':4A,35B,54B,94C,104C,143C 'caus':73B,145C 'corrupt':7A,70B,147C 'crash':10A 'custom':3A,53B,93C,142C 'custom-categori':2A,52B,141C 'cve':13A,16A 'denial':75B,149C 'dissect':48B,123C 'fix':158C 'four':31B,99C 'four-byt':30B,98C 'get':92C 'host':26B,125C 'id':114C 'initi':126C 'interact':154C 'ipaddress':117C 'issu':156C 'match':6A,51B,95C,140C 'monitor':12A,21B,62B,86C,133C 'ndpi':91C,101C 'network':20B,63B,84C,134C 'network-monitor':19B 'ntopng':1A,22B,27B,78C 'packag':23B 'packet':5A,49B,68B,122C,138C 'pointer':108C 'prior':88C 'protocol':34B,103C 'protocol-categori':33B,102C 'reloadblacklist':118C 'remot':57B,128C 'rule':55B,144C 'segment':64B,135C 'self':25B 'self-host':24B 'send':66B,137C 'servic':77B,151C 'src/ipaddress.cpp':120C 'stack':9A,45B,72B,146C 'traffic':85C 'two':40B,112C 'two-byt':39B,111C 'unauthent':58B,129C 'user':153C 'valu':36B,105C 'variabl':42B,115C 'version':160C 'web':82C 'web-bas':81C 'without':152C 'write':28B,96C","nicknames":[],"mitigations":[],"who_affected":"Teams running ntopng to monitor network traffic, especially where a monitored segment can be reached by untrusted hosts. The flaw is reached during packet dissection and host initialization, and only packets matching custom-category rules trigger the bad write, so deployments without custom categories are less exposed. Teams on ntopng 6.7.260721 or later are not affected.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["medium","networkmonitoring","ntopng","package","selfhosted"],"campaign_type":null,"first_public_at":"2026-07-21T07:34:28+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","cvss_by":"security-advisories@github.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-97371","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97371","severity":null,"published_at":"2026-11-05T17:18:22+00:00","modified_at":"2026-11-05T17:18:22+00:00","first_seen_at":"2026-11-05T17:40:05+00:00","fetched_at":"2026-11-05T17:40:05+00:00","note":null}],"documents":[{"id":78142,"url":"https://github.com/ntop/ntopng/commit/96acb6187950a6a49ca827e49973c3e0c27ea664","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":78143,"url":"https://github.com/ntop/ntopng/security/advisories/GHSA-26jm-9qfw-89w7","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-07-21T07:34:28+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.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"}