{"id":"CVE-2026-119760","kind":"vulnerability","aliases":["CVE-2026-119760"],"related":[],"title":"sniproxy: overlong hostname triggers NULL dereference that crashes the daemon","description":"sniproxy through 0.7.0 contains a NULL pointer dereference vulnerability in resolv_cancel() that allows remote unauthenticated attackers to crash the daemon by sending overlong hostnames. Attackers can send a 254 or 255 character TLS SNI name or HTTP Host header matching a wildcard backend, then close the connection to terminate the proxy.","summary":"sniproxy through 0.7.0 has a NULL pointer dereference in resolv_cancel() that an unauthenticated remote client can trigger. Sending a 254 or 255 character TLS SNI name or HTTP Host header matching a wildcard backend, then closing the connection, terminates the proxy.","severity":"high","cvss":8.7,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"sniproxy","fixed":[],"affected":"<= 0.7.0","ecosystem":"generic"}],"ecosystems":[],"tags":["dos","reverse-proxy","runtime","self-hosted","sniproxy"],"not_affected_if":["dns-resolution-disabled","no-wildcard-backend","not-running-sniproxy"],"how_to_check":"- Run sniproxy -V or check your package (Debian 0.7.0-1 is affected).\n- Check the config for a table entry whose backend is a wildcard '*' (e.g. '.* *'); without a wildcard backend the reported trigger path does not apply.\n- Check sniproxy was built with DNS resolution (--enable-dns); the crash is in the resolver path.","fix":null,"status":"open","published_at":"2026-10-30T18:17:26+00:00","first_seen_at":"2026-10-30T18:55:29+00:00","triaged_at":"2026-10-30T18:56:35+00:00","updated_at":"2026-10-30T19:00:25+00:00","category":"runtime","confidence":0.8,"triage":{"at":"2026-10-30T18:56:35Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"internet","title":"sniproxy: overlong hostname triggers NULL dereference that crashes the daemon","impact":"medium","summary":"sniproxy through 0.7.0 has a NULL pointer dereference in resolv_cancel() that an unauthenticated remote client can trigger. Sending a 254 or 255 character TLS SNI name or HTTP Host header matching a wildcard backend, then closing the connection, terminates the proxy.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["sniproxy","self-hosted","reverse-proxy"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"remote attackers repeatedly crash the proxy daemon, causing denial of service","analyst_note":"Confirm the fixed sniproxy version and whether a wildcard backend is required, using the NVD entry at https://nvd.nist.gov/vuln/detail/CVE-2026-119760 and the upstream project.","how_to_check":"- Check the installed sniproxy version against the affected range (through 0.7.0), for example with `sniproxy -v` or the package manager.\n- Look for a wildcard backend entry in the sniproxy configuration file, since the source describes that as the trigger path.","plain_action":"","needs_analyst":true,"not_affected_if":["not-running-sniproxy"],"who_is_affected":"Teams running sniproxy as a TLS SNI or HTTP Host proxy, especially with wildcard backend entries, are exposed to remote crashes. Deployments that do not run sniproxy, or that run a version later than 0.7.0 once a fix is confirmed, can skip it.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000727,"input_tokens":4157,"output_tokens":622,"severity_before":"high"},"analyst_status":"done","analyst_note":"Confirm the fixed sniproxy version and whether a wildcard backend is required, using the NVD entry at https://nvd.nist.gov/vuln/detail/CVE-2026-119760 and the upstream project.","search":"'-119760':13A,16A '-2026':12A,15A '0.7.0':29B,71C '254':47B,98C '255':49B,100C 'allow':82C 'attack':85C,94C 'backend':61B,112C 'cancel':37B,80C 'charact':50B,101C 'client':42B 'close':63B,114C 'connect':65B,116C 'contain':72C 'crash':8A,87C 'cve':11A,14A 'daemon':10A,89C 'derefer':6A,34B,76C 'dos':18B 'header':57B,108C 'host':25B,56B,107C 'hostnam':3A,93C 'http':55B,106C 'match':58B,109C 'name':53B,104C 'null':5A,32B,74C 'overlong':2A,92C 'pointer':33B,75C 'proxi':21B,68B,120C 'remot':41B,83C 'resolv':36B,79C 'revers':20B 'reverse-proxi':19B 'runtim':22B 'self':24B 'self-host':23B 'send':45B,91C,96C 'sni':52B,103C 'sniproxi':1A,26B,27B,69C 'sniproxy':17A 'termin':66B,118C 'tls':51B,102C 'trigger':4A,44B 'unauthent':40B,84C 'vulner':77C 'wildcard':60B,111C","nicknames":[],"mitigations":[],"who_affected":"Teams running sniproxy 0.7.0 (including the Debian 0.7.0-1 package) with a wildcard backend entry and DNS resolution enabled. Any unauthenticated client can crash the proxy by sending a 254 or 255 character SNI or Host name and closing the connection. If you only use fixed backends or do not run sniproxy, you can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"first_public_at":"2026-10-30T18:17:26+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-119760","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119760","severity":null,"published_at":"2026-10-30T18:17:26+00:00","modified_at":"2026-10-30T18:17:26+00:00","first_seen_at":"2026-10-30T18:55:29+00:00","fetched_at":"2026-10-30T18:55:29+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-119760:1185","url":null,"severity":null,"published_at":"2026-10-30T19:00:25+00:00","modified_at":"2026-10-30T19:00:25+00:00","first_seen_at":"2026-10-30T19:00:25+00:00","fetched_at":"2026-10-30T19:00:25+00:00","note":"Upstream issue #411 (open, maintainer's own tracker) confirms: 254/255-char SNI/Host matching a wildcard backend ('*' target) -> valid_hostname accepts up to 255, libudns rejects >253, query handle NULL, client close calls resolv_cancel(NULL). No upstream release or fix; only a fork (renaudallard) commit guards the call, and that commit message describes it as use-after-free guard, so not verified as the fix. Affected 0.7.0 (Debian 0.7.0-1 built with --enable-dns). Nothing marked verified."}],"documents":[{"id":25348,"url":"https://github.com/dlundquist/sniproxy/issues/411","title":"sniproxy issue #411: NULL resolv_cancel on 254/255-char hostname (open)","kind":"issue","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":25349,"url":"https://www.vulncheck.com/advisories/sniproxy-through-0.7.0-null-pointer-dereference-via-resolv-cancel","title":"VulnCheck advisory: sniproxy through 0.7.0 NULL Pointer Dereference via resolv_cancel()","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"describes","confidence":null,"note":null},{"id":25350,"url":"https://github.com/renaudallard/sniproxy/commit/d5d78290c8fe15d9aa12185d2c57739b7b0c6a6b","title":"renaudallard/sniproxy fork commit guarding resolv_cancel (not upstream)","kind":"other","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"mentions","confidence":null,"note":null}],"notice":"Free to read at a human pace. 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