{"id":"CVE-2026-24061","kind":"vulnerability","aliases":["CVE-2026-24061"],"related":[],"title":"telnetd in GNU Inetutils through 2.7 allows remote authentication bypass via a \"-f root\" value for the USER…","description":"GNU InetUtils contains an argument injection vulnerability in telnetd that could allow for remote authentication bypass via a \"-f root\" value for the USER environment variable.\n\nCISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","summary":"GNU InetUtils telnetd passes a USER environment variable value of \"-f root\" as an argument, which skips the login password check. A remote attacker can log in as root without credentials.","severity":"critical","cvss":9.8,"epss":null,"exploited":true,"exploited_at":"2026-01-26T00:00:00+00:00","products":[{"name":"GNU InetUtils","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"gnu inetutils","fixed":[],"affected":">= 1.9.3, <= 2.7","ecosystem":"vendor"},{"name":"debian linux","fixed":[],"affected":"= 11.0","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","gnu-inetutils","infrastructure","linux","self-hosted","telnetd"],"not_affected_if":["ssh-only-access","telnetd-not-running"],"how_to_check":"Check whether telnetd from GNU InetUtils is running: ss -tlnp | grep :23","fix":"Apply vendor mitigations per CISA guidance, or disable telnetd and use SSH instead.","status":"open","published_at":"2026-01-21T07:16:01+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:42:30+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-10-23T20:42:30Z","model":"claude-haiku-5-5","output":{"fix":"Apply vendor mitigations per CISA guidance, or disable telnetd and use SSH instead.\nUnknown whether a fixed InetUtils version is named in the sources.","reach":"network","summary":"GNU InetUtils telnetd passes a USER environment variable value of \"-f root\" as an argument, which skips the login password check. A remote attacker can log in as root without credentials.","category":"infrastructure","who_cares":["telnetd","gnu-inetutils","linux","self-hosted"],"confidence":0.7,"needs_auth":"no","worst_case":"Remote attacker gets root shell on the telnet server without a password","analyst_note":"Find the fixed InetUtils version and vendor mitigation text at the GNU advisory; the sources here do not name them.","how_to_check":"Check whether telnetd from GNU InetUtils is running: ss -tlnp | grep :23\nUnknown whether the sources give a specific version range or config file to inspect.\nUnknown whether a patched version exists in the sources.","needs_analyst":true,"not_affected_if":["telnetd-not-running","ssh-only-access"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000465,"input_tokens":2530,"output_tokens":424,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-01':110C '-2026':20A,23A '-24061':21A,24A '2.7':6A '22':109C 'action':100C 'allow':7A,83C 'appli':101C 'applic':107C 'argument':55B,76C 'attack':64B 'authent':9A,86C 'bod':108C 'bypass':10A,87C 'check':61B 'cisa':98C 'cloud':113C 'contain':74C 'could':82C 'credenti':71B 'cve':19A,22A 'debian':29A 'discontinu':116C 'environ':47B,96C 'exploit':31B 'f':13A,51B,90C 'follow':106C 'gnu':3A,25A,27A,33B,41B,72C 'gnu-inetutil':32B 'guidanc':111C 'host':39B 'inetutil':4A,34B,42B,73C 'inetutils':26A,28A 'infrastructur':35B 'inject':77C 'instruct':105C 'linux':30A,36B 'log':66B 'login':59B 'mitig':102C,122C 'pass':44B 'password':60B 'per':103C 'product':120C 'remot':8A,63B,85C 'requir':99C 'root':14A,52B,69B,91C 'self':38B 'self-host':37B 'servic':114C 'skip':57B 'telnetd':1A,40B,43B,80C 'unavail':124C 'use':117C 'user':18A,46B,95C 'valu':15A,49B,92C 'variabl':48B,97C 'vendor':104C 'via':11A,88C 'vulner':78C 'without':70B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-01-21T07:16:01+00:00","kev":{"dateAdded":"2026-01-26","dueDate":"2026-02-16","requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"cve@mitre.org","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2026-24061","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-24061","severity":null,"published_at":"2026-01-26T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T11:39:14+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-24061","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-24061","severity":null,"published_at":"2026-01-21T07:16:01+00:00","modified_at":"2026-09-30T11:47:02+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+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"}