{"id":"CVE-2026-121505","kind":"vulnerability","aliases":["CVE-2026-121505"],"related":[],"title":"NTPsec: NTS client over-reads memory and leaks pointers to servers","description":"An out-of-bounds read in the NTS-KE client response parser (nts_client_process_response_core) in NTPsec before 1.2.4 allows a malicious NTS-KE server to read the client's stack memory, including pointers that defeat ASLR, which the client then sends in cleartext as NTS cookies, via an NTS-KE record whose declared length exceeds the data received.","summary":"A bug in NTPsec's NTS-KE client response parser lets a malicious NTS-KE server make the client read past its buffer. The client then sends that stack memory, including pointers that weaken ASLR, back in cleartext as NTS cookies.","severity":"low","cvss":3.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ntp","ntpsec","nts","package","time-sync"],"not_affected_if":["no-nts-client","trusted-nts-servers-only"],"how_to_check":"- Check the installed NTPsec version with `ntpq --version` or `ntpd --version`\n- Look for NTS client use in the NTP configuration (`nts` keyword in ntp.conf or ntpsec config)","fix":"- NTPsec `1.2.4` or later (the advisory states fixes start at `before 1.2.4`)","status":"open","published_at":"2026-11-03T15:17:37+00:00","first_seen_at":"2026-11-03T15:22:01+00:00","triaged_at":"2026-11-03T15:24:47+00:00","updated_at":"2026-11-03T15:24:47+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-03T15:24:47Z","model":"claude-haiku-5-5","output":{"fix":"- NTPsec `1.2.4` or later (the advisory states fixes start at `before 1.2.4`)","reach":"network","title":"NTPsec: NTS client over-reads memory and leaks pointers to servers","impact":"low","summary":"A bug in NTPsec's NTS-KE client response parser lets a malicious NTS-KE server make the client read past its buffer. The client then sends that stack memory, including pointers that weaken ASLR, back in cleartext as NTS cookies.","audience":"developers","category":"package","nicknames":[],"who_cares":["ntpsec","ntp","nts","time-sync"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"Stack memory leaks to a malicious time server, weakening ASLR.","analyst_note":"","how_to_check":"- Check the installed NTPsec version with `ntpq --version` or `ntpd --version`\n- Look for NTS client use in the NTP configuration (`nts` keyword in ntp.conf or ntpsec config)","plain_action":"","needs_analyst":false,"not_affected_if":["no-nts-client","trusted-nts-servers-only"],"who_is_affected":"Only systems running the NTPsec time daemon as an NTS client that connect to a malicious or compromised NTS-KE server are exposed. Servers that do not use NTS key establishment, or that only talk to trusted NTS servers, are at much lower risk.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"low"},"cost_usd":0.000683,"input_tokens":4158,"output_tokens":535,"severity_before":"low"},"analyst_status":null,"analyst_note":null,"search":"'-121505':15A,18A '-2026':14A,17A '1.2.4':91C 'allow':92C 'aslr':62B,110C 'back':63B 'bound':73C 'buffer':50B 'bug':27B 'cleartext':65B,117C 'client':3A,34B,46B,52B,80C,84C,102C,113C 'cooki':68B,120C 'core':87C 'cve':13A,16A 'data':132C 'declar':128C 'defeat':109C 'exceed':130C 'includ':58B,106C 'ke':33B,42B,79C,97C,125C 'leak':9A 'length':129C 'let':37B 'make':44B 'malici':39B,94C 'memori':7A,57B,105C 'ntp':19B 'ntpsec':1A,20B,29B,89C 'nts':2A,21B,32B,41B,67B,78C,83C,96C,119C,124C 'nts-ke':31B,40B,77C,95C,123C 'out-of-bound':70C 'over-read':4A 'packag':22B 'parser':36B,82C 'past':48B 'pointer':10A,59B,107C 'process':85C 'read':6A,47B,74C,100C 'receiv':133C 'record':126C 'respons':35B,81C,86C 'send':54B,115C 'server':12A,43B,98C 'stack':56B,104C 'sync':25B 'time':24B 'time-sync':23B 'via':121C 'weaken':61B 'whose':127C","nicknames":[],"mitigations":[],"who_affected":"Only systems running the NTPsec time daemon as an NTS client that connect to a malicious or compromised NTS-KE server are exposed. Servers that do not use NTS key establishment, or that only talk to trusted NTS servers, are at much lower risk.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["low","ntp","ntpsec","nts","package","timesync"],"first_public_at":"2026-11-03T15:17:37+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","cvss_by":"cve@gitlab.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121505","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121505","severity":null,"published_at":"2026-11-03T15:17:37+00:00","modified_at":"2026-11-03T15:17:37+00:00","first_seen_at":"2026-11-03T15:22:01+00:00","fetched_at":"2026-11-03T15:22:01+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"}