{"id":"CVE-2023-27997","published":"2023-06-13T09:15:16Z","modified":"2026-07-31T04:16:43Z","title":"Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability","vendor":"Fortinet","product":"FortiOS and FortiProxy SSL-VPN","tier":"core","eol":null,"description":{"text":"A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.","provenance":"source","from":"NVD"},"summary":{"text":"A heap-based buffer overflow in the SSL-VPN component of Fortinet's FortiOS and FortiProxy products allows the flaw to be triggered by specially crafted requests. A remote attacker can exploit it to execute arbitrary code or commands, requiring only network access to the SSL-VPN service, with no authentication or user interaction needed.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T06:58:15Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.85689,"percentile":0.99725,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2023-06-13","dueDate":"2023-07-04","ransomware":true,"requiredAction":"Apply updates per vendor instructions.","notes":"https://www.fortiguard.com/psirt/FG-IR-23-097;  https://nvd.nist.gov/vuln/detail/CVE-2023-27997","provenance":"source"},"vulncheckKev":{"dateAdded":"2023-06-12","exploitedFirstSeen":"2023-06-12","ransomware":true,"evidence":[{"url":"https://www.fortinet.com/blog/psirt-blogs/analysis-of-cve-2023-27997-and-clarifications-on-volt-typhoon-campaign","date":"2023-06-12"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2023-06-13"},{"url":"https://information.rapid7.com/rs/411-NAK-970/images/Rapid7-2023-Mid-Year-Threat-Review.pdf","date":"2023-08-17"},{"url":"https://blog.lumen.com/routers-roasting-on-an-open-firewall-the-kv-botnet-investigation/","date":"2023-12-13"},{"url":"https://www.fortinet.com/blog/psirt-blogs/importance-of-patching-an-analysis-of-the-exploitation-of-n-day-vulnerabilities","date":"2024-02-07"},{"url":"https://www.tenable.com/blog/cve-2024-21762-critical-fortinet-fortios-out-of-bound-write-ssl-vpn-vulnerability","date":"2024-02-09"},{"url":"https://www.rapid7.com/blog/post/2024/02/12/etr-critical-fortinet-fortios-cve-2024-21762-exploited/","date":"2024-02-12"},{"url":"https://www.rapid7.com/globalassets/_pdfs/research/rapid7_2024_attack_intelligence_report.pdf","date":"2024-05-21"},{"url":"https://labs.withsecure.com/publications/mass-exploitation-the-vulnerable-edge-of-enterprise-security","date":"2024-06-12"},{"url":"https://hub.dragos.com/hubfs/Reports/Dragos_Report_Cyber_Threat_Perspective_Nordic_Feb24_Complete.pdf","date":"2024-06-28"}],"evidenceTotal":44,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-787","name":"Out-of-bounds Write"},{"id":"CWE-122","name":"Heap-based Buffer Overflow"}],"references":[{"url":"https://fortiguard.com/psirt/FG-IR-23-097","tags":["Vendor Advisory"]},{"url":"https://fortiguard.com/psirt/FG-IR-23-097","tags":["Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-27997","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Buffer Overflow","mappingType":"exploitation_technique","evidence":[],"comment":"This buffer overflow vulnerability allows adversaries to remotely execute arbitrary code via specially crafted requests.\n\nAdversaries have been observed adding accounts to config files ","confidence":"high"},{"id":"T1574","name":"Hijack Execution Flow","tactics":["execution","stealth"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Buffer Overflow","mappingType":"exploitation_technique","evidence":[],"comment":"This buffer overflow vulnerability allows adversaries to remotely execute arbitrary code via specially crafted requests.\n\nAdversaries have been observed adding accounts to config files ","confidence":"high"},{"id":"T1136","name":"Create Account","tactics":["persistence"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Buffer Overflow","mappingType":"primary_impact","evidence":[],"comment":"This buffer overflow vulnerability allows adversaries to remotely execute arbitrary code via specially crafted requests.\n\nAdversaries have been observed adding accounts to config files ","confidence":"high"}],"reports":[{"id":"SRC-d849a763c1dde7c77634","title":"Spot the Difference: Earth Kasha's New LODEINFO Campaign And The Correlation Analysis With The APT10 Umbrella","publisher":"trendmicro.com","url":"https://www.trendmicro.com/en_us/research/24/k/lodeinfo-campaign-of-earth-kasha.html","date":"2024-11-19","mentions":[{"quote":"We observed that vulnerabilities of enterprise products, such as Array AG (CVE-2023-28461), Proself (CVE-2023-45727) and FortiOS/FortiProxy (CVE-2023-27997), were abused in the wild.","start":2002,"end":2184},{"quote":"Furthermore, Volt Typhoon, which is a state-sponsored actor based in China documented by Microsoft, was reportedly carrying out the exploit against FortiOS/FortiProxy (CVE-2023-27997), which was also used in the LODEINFO Campaign #2 in 2023.","start":26498,"end":26739},{"quote":"The vulnerability of CVE-2023-27997 was 0-day at the time of usage in both campaigns by Volt Typhoon and Earth Kasha, leading us to the assumption that the 0-day vulnerability was possibly shared or there might be a third-party entity, such as access brokers, specialized in facilitating Initial Access.","start":26969,"end":27272}]}],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2023-31722","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2023-31722","exploited":true,"exploitedSince":"2023-06-13","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":11,"skipped":1,"earliest":"2023-06-16","earliestUrl":"https://github.com/rio128128/CVE-2023-27997-POC","repos":[{"name":"BishopFox/CVE-2023-27997-check","url":"https://github.com/BishopFox/CVE-2023-27997-check","stars":134,"created":"2023-06-16"},{"name":"lexfo/xortigate-cve-2023-27997","url":"https://github.com/lexfo/xortigate-cve-2023-27997","stars":63,"created":"2023-10-12"},{"name":"rio128128/CVE-2023-27997-POC","url":"https://github.com/rio128128/CVE-2023-27997-POC","stars":27,"created":"2023-06-16"},{"name":"delsploit/CVE-2023-27997","url":"https://github.com/delsploit/CVE-2023-27997","stars":9,"created":"2023-10-12"},{"name":"TechinsightsPro/ShodanFortiOS","url":"https://github.com/TechinsightsPro/ShodanFortiOS","stars":2,"created":"2023-07-11"}]},"first":{"date":"2023-06-16","source":"PoC-in-GitHub","url":"https://github.com/rio128128/CVE-2023-27997-POC"},"provenance":"source"},"detections":{"cveRules":[{"title":"Potential CVE-2023-27997 Exploitation Indicators","id":"31e4e649-7394-4fd2-9ae7-dbc61eebb550","level":"medium","status":"test","path":"rules-emerging-threats/2023/Exploits/CVE-2023-27997/web_cve_2023_27997_pre_authentication_rce.yml","url":"https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2023/Exploits/CVE-2023-27997/web_cve_2023_27997_pre_authentication_rce.yml","techniques":["T1190"]}]},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190","T1574"],"provenance":"source"},{"stage":"primary","techniques":["T1136"],"provenance":"source"}],"timeline":[{"date":"2023-06-12","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.fortinet.com/blog/psirt-blogs/analysis-of-cve-2023-27997-and-clarifications-on-volt-typhoon-campaign","provenance":"source"},{"date":"2023-06-13","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-27997","provenance":"source"},{"date":"2023-06-13","kind":"kev","label":"Added to CISA KEV (known ransomware use)","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2023-06-13","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2023-31722","provenance":"source"},{"date":"2023-06-16","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/rio128128/CVE-2023-27997-POC","provenance":"source"},{"date":"2024-11-19","kind":"report","label":"Named in trendmicro.com: Spot the Difference: Earth Kasha's New LODEINFO Campaign And The Correlation Analysis With The…","url":"https://www.trendmicro.com/en_us/research/24/k/lodeinfo-campaign-of-earth-kasha.html","provenance":"machine"}],"speed":{"daysToPublicExploit":3,"firstExploitFrom":"PoC-in-GitHub","daysToKev":0},"priority":{"score":83.7,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 1235 days ago"},{"name":"Known ransomware use","points":10.0,"detail":"CISA KEV and VulnCheck KEV: Known"},{"name":"EPSS percentile","points":19.95,"detail":"percentile 0.9972"},{"name":"Named in threat reports","points":3.87,"detail":"1 report"},{"name":"Public exploit code","points":5.0,"detail":"11 PoC-in-GitHub repos"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":6.86,"detail":"base score 9.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}