{"id":"CVE-2026-57194","kind":"vulnerability","aliases":["CVE-2026-57194"],"related":[],"title":"Asterisk: crafted UNISTIM packet overflows phone number field, crashing server","description":"Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an out-of-bounds write in `chan_unistim` `DIALPAGE` digit handling can overflow the `phone_number` field and crash Asterisk when an attacker sends a carefully crafted incoming request packet. The `chan_unistim` module must be loaded and configured with a valid `UNISTIM UDP port` that the attacker can reach. The attacker must register as a configured `phone MAC`, or the deployment must have an equivalent `production/autoprovisioning` path that allows the client to reach the main page. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.","summary":"Asterisk's chan_unistim module has an out-of-bounds write in DIALPAGE digit handling that overflows the phone_number field. A crafted incoming packet can crash Asterisk, causing a denial of service.","severity":"medium","cvss":5.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["asterisk","runtime","self-hosted","telephony","unistim"],"not_affected_if":["chan-unistim-not-loaded","no-unistim-port-exposed"],"how_to_check":"- Check whether the `chan_unistim` module is loaded in Asterisk (for example with `asterisk -rx \"module show like unistim\"`).\n- Check the Asterisk version with `asterisk -V` and compare it to the fixed releases.\n- Check whether `unistim.conf` defines a UNISTIM UDP port reachable from untrusted networks.","fix":"- Upgrade Asterisk to `20.20.1`, `21.12.3`, `22.10.1` or `23.4.1`.\n- For Certified Asterisk, upgrade to `20.7-cert11` or `22.8-cert3`.\n- If the UNISTIM module is not needed, unload or remove `chan_unistim`.","status":"open","published_at":"2026-10-27T17:17:01+00:00","first_seen_at":"2026-10-27T17:32:46+00:00","triaged_at":"2026-10-27T17:34:51+00:00","updated_at":"2026-10-27T17:34:51+00:00","category":"runtime","confidence":0.8,"triage":{"at":"2026-10-27T17:34:51Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Asterisk to `20.20.1`, `21.12.3`, `22.10.1` or `23.4.1`.\n- For Certified Asterisk, upgrade to `20.7-cert11` or `22.8-cert3`.\n- If the UNISTIM module is not needed, unload or remove `chan_unistim`.","reach":"network","title":"Asterisk: crafted UNISTIM packet overflows phone number field, crashing server","impact":"medium","summary":"Asterisk's chan_unistim module has an out-of-bounds write in DIALPAGE digit handling that overflows the phone_number field. A crafted incoming packet can crash Asterisk, causing a denial of service.","category":"runtime","nicknames":[],"who_cares":["asterisk","telephony","unistim","self-hosted"],"confidence":0.8,"needs_auth":"unknown","worst_case":"Asterisk crashes and telephony service goes down","analyst_note":"","how_to_check":"- Check whether the `chan_unistim` module is loaded in Asterisk (for example with `asterisk -rx \"module show like unistim\"`).\n- Check the Asterisk version with `asterisk -V` and compare it to the fixed releases.\n- Check whether `unistim.conf` defines a UNISTIM UDP port reachable from untrusted networks.","needs_analyst":false,"not_affected_if":["chan-unistim-not-loaded","no-unistim-port-exposed"],"who_is_affected":"Deployments that load chan_unistim and expose its UNISTIM UDP port to a network the attacker can reach, such as Unistim phone systems. The attacker must register as a configured phone MAC, or the deployment must have an autoprovisioning path that lets the client reach the main page. Systems that do not load chan_unistim are not affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000685,"input_tokens":3528,"output_tokens":664,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-57194':13A,16A '20.20.1':72C,167C '20.7':79C,174C '21.12.3':73C,168C '22.10.1':74C,169C '22.8':81C,176C '23.4.1':75C,170C 'allow':153C 'asterisk':1A,17B,24B,52B,58C,71C,78C,103C,166C,173C 'attack':106C,131C,135C 'bound':34B,87C 'branch':64C 'care':109C 'caus':53B 'cert11':80C,175C 'cert3':82C,177C 'certifi':77C,172C 'chan':26B,90C,115C 'client':155C 'configur':122C,140C 'craft':2A,47B,110C 'crash':9A,51B,102C 'cve':11A,14A 'denial':55B 'deploy':145C 'dialpag':37B,92C 'digit':38B,93C 'equival':149C 'exchang':65C 'field':8A,45B,100C 'fix':164C 'handl':39B,94C 'host':21B 'incom':48B,111C 'issu':162C 'load':120C 'mac':142C 'main':159C 'modul':28B,117C 'must':118C,136C,146C 'number':7A,44B,99C 'open':61C 'out-of-bound':31B,84C 'overflow':5A,41B,96C 'packet':4A,49B,113C 'page':160C 'path':151C 'phone':6A,43B,98C,141C 'port':128C 'prior':69C 'privat':63C 'production/autoprovisioning':150C 'reach':133C,157C 'regist':137C 'request':112C 'runtim':18B 'self':20B 'self-host':19B 'send':107C 'server':10A 'servic':57B 'sourc':62C 'telephoni':22B,67C 'toolkit':68C 'udp':127C 'unistim':3A,23B,27B,91C,116C,126C 'valid':125C 'write':35B,88C","nicknames":[],"mitigations":[],"who_affected":"Deployments that load chan_unistim and expose its UNISTIM UDP port to a network the attacker can reach, such as Unistim phone systems. The attacker must register as a configured phone MAC, or the deployment must have an autoprovisioning path that lets the client reach the main page. Systems that do not load chan_unistim are not affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T17:17:01+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","cvss_by":"security-advisories@github.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-57194","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-57194","severity":null,"published_at":"2026-10-27T17:17:01+00:00","modified_at":"2026-10-27T17:17:01+00:00","first_seen_at":"2026-10-27T17:32:46+00:00","fetched_at":"2026-10-27T17:32:46+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"}