{"id":"CVE-2026-113866","kind":"vulnerability","aliases":["CVE-2026-113866"],"related":[],"title":"Thunderbird: account setup leaks user password over plain HTTP","description":"When setting up an account, Thunderbird's Exchange AutoDiscover lookup also queried the domain's AutoDiscover service over plain HTTP. Due to a bug, that unencrypted request included the credentials the user had entered, allowing a network attacker to obtain the user's password. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.","summary":"When Thunderbird sets up an account, its Exchange AutoDiscover lookup also sends a request to the domain's AutoDiscover service over unencrypted HTTP. That request carried the password the user typed, so a network attacker can read it.","severity":"medium","cvss":5.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["desktop-email","exchange","package","thunderbird"],"not_affected_if":["already-on-fixed-version","no-exchange-account-setup"],"how_to_check":"- Run `thunderbird --version` (or check Help > About Thunderbird) and compare against the fixed versions.\n- unknown","fix":"- Update Thunderbird to `158.0.1` or `153.5.1`, whichever matches your release line.","status":"open","published_at":"2026-10-20T20:17:19+00:00","first_seen_at":"2026-10-23T21:57:21+00:00","triaged_at":"2026-10-25T04:08:39+00:00","updated_at":"2026-10-25T04:08:39+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-25T04:08:39Z","model":"claude-haiku-5-5","output":{"fix":"- Update Thunderbird to `158.0.1` or `153.5.1`, whichever matches your release line.","reach":"network","title":"Thunderbird: account setup leaks user password over plain HTTP","impact":"medium","summary":"When Thunderbird sets up an account, its Exchange AutoDiscover lookup also sends a request to the domain's AutoDiscover service over unencrypted HTTP. That request carried the password the user typed, so a network attacker can read it.","category":"package","nicknames":[],"who_cares":["thunderbird","desktop-email","exchange"],"confidence":0.6,"needs_auth":"no","worst_case":"Network attacker obtains the user's mail account password in cleartext.","analyst_note":"","how_to_check":"- Run `thunderbird --version` (or check Help > About Thunderbird) and compare against the fixed versions.\n- unknown","needs_analyst":false,"not_affected_if":["already-on-fixed-version","no-exchange-account-setup"],"who_is_affected":"Anyone running Thunderbird versions before the fixed releases who sets up an Exchange account over a network an attacker can observe. The exposure comes from the account-setup step, so an existing configured account that is not re-added is less exposed. The sources do not say whether a specific account type or server configuration changes the risk.","user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"medium"},"cost_usd":0.00058,"input_tokens":3354,"output_tokens":490,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-113866':12A,15A '-2026':11A,14A '153.5.1':112C '158.0.1':109C 'account':2A,27B,63C 'allow':93C 'also':32B,69C 'attack':56B,96C 'autodiscov':30B,40B,67C,74C 'bug':82C 'carri':47B 'credenti':88C 'cve':10A,13A 'desktop':17B 'desktop-email':16B 'domain':38B,72C 'due':79C 'email':18B 'enter':92C 'exchang':19B,29B,66C 'fix':106C 'http':9A,44B,78C 'includ':86C 'leak':4A 'lookup':31B,68C 'network':55B,95C 'obtain':98C 'packag':20B 'password':6A,49B,102C 'plain':8A,77C 'queri':70C 'read':58B 'request':35B,46B,85C 'send':33B 'servic':41B,75C 'set':24B,60C 'setup':3A 'thunderbird':1A,21B,23B,64C,108C,111C 'type':52B 'unencrypt':43B,84C 'user':5A,51B,90C,100C 'vulner':104C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Thunderbird versions before the fixed releases who sets up an Exchange account over a network an attacker can observe. The exposure comes from the account-setup step, so an existing configured account that is not re-added is less exposed. The sources do not say whether a specific account type or server configuration changes the risk.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-20T20:17:19+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","cvss_by":"134c704f-9b21-4f2e-91b3-4a467353bcc0","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-113866","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-113866","severity":null,"published_at":"2026-10-20T20:17:19+00:00","modified_at":"2026-10-22T17:36:46+00:00","first_seen_at":"2026-10-23T21:57:21+00:00","fetched_at":"2026-10-23T22:28:58+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"}