{"id":"CVE-2021-20038","published":"2021-12-08T10:15:07Z","modified":"2026-06-17T03:33:11Z","title":"SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability","vendor":"SonicWall","product":"SMA 100 Appliances","tier":"core","eol":null,"description":{"text":"A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote unauthenticated attacker to potentially execute code as a 'nobody' user in the appliance. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.","provenance":"source","from":"NVD"},"summary":{"text":"A stack-based buffer overflow in the mod_cgi module's handling of environment variables in the Apache httpd server on SonicWall SMA 100 Appliances (SMA 200, 210, 400, 410 and 500v) lets an attacker trigger memory corruption. A remote, unauthenticated attacker with network access to the appliance, requiring no user interaction and no special configuration, could potentially execute code as the 'nobody' user on the appliance.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T06:57:03Z"},"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":0.99912,"percentile":0.99967,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2022-01-28","dueDate":"2022-02-11","ransomware":true,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-20038","provenance":"source"},"vulncheckKev":{"dateAdded":"2022-01-28","exploitedFirstSeen":"2022-01-28","ransomware":true,"evidence":[{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2022-01-28"},{"url":"https://www.cisa.gov/uscert/ncas/alerts/aa23-040a","date":"2022-04-11"},{"url":"https://cisa.gov/news-events/alerts/2022/04/27/2021-top-routinely-exploited-vulnerabilities","date":"2022-04-28"},{"url":"https://cisa.gov/news-events/cybersecurity-advisories/aa22-117a","date":"2022-04-28"},{"url":"https://cisa.gov/news-events/cybersecurity-advisories/aa23-040a","date":"2023-02-09"},{"url":"https://4502402.fs1.hubspotusercontent-na1.net/hubfs/4502402/Ransomware%20-%20Index%20Update%20Q1%202023.pdf","date":"2023-05-15"},{"url":"https://cisa.gov/news-events/cybersecurity-advisories/aa23-215a","date":"2023-08-03"},{"url":"https://information.rapid7.com/rs/411-NAK-970/images/Rapid7-2023-Mid-Year-Threat-Review.pdf","date":"2023-08-17"},{"url":"https://www.cisa.gov/sites/default/files/2024-07/aa24-207a-dprk-cyber-group-conducts-global-espionage-campaign.pdf","date":"2024-07-25"},{"url":"https://www.sygnia.co/blog/abyss-locker-ransomware-attack-analysis/","date":"2025-02-04"}],"evidenceTotal":13,"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-121","name":"Stack-based Buffer Overflow"},{"id":"CWE-787","name":"Out-of-bounds Write"}],"references":[{"url":"https://github.com/jbaines-r7/badblood","tags":["Exploit","Third Party Advisory"]},{"url":"https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026","tags":["Vendor Advisory"]},{"url":"https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/","tags":["Exploit","Third Party Advisory"]},{"url":"https://github.com/jbaines-r7/badblood","tags":["Exploit","Third Party Advisory"]},{"url":"https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026","tags":["Vendor Advisory"]},{"url":"https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/","tags":["Exploit","Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20038","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Remote unauthenticated exploit of public-facing httpd server","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"allows a remote unauthenticated attacker to potentially execute code","start":113,"end":181}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Code execution as nobody user","mappingType":"primary_impact","evidence":[{"from":"description","quote":"allows a remote unauthenticated attacker to potentially execute code","start":113,"end":181}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-7501","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-7501","exploited":true,"exploitedSince":"2022-01-28","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":3,"skipped":0,"earliest":"2022-01-11","earliestUrl":"https://github.com/jbaines-r7/badblood","repos":[{"name":"jbaines-r7/badblood","url":"https://github.com/jbaines-r7/badblood","stars":95,"created":"2022-01-11"},{"name":"vesperp/CVE-2021-20038-SonicWall-RCE","url":"https://github.com/vesperp/CVE-2021-20038-SonicWall-RCE","stars":1,"created":"2022-08-08"},{"name":"anir0y/sonicwall-audit-toolkit","url":"https://github.com/anir0y/sonicwall-audit-toolkit","stars":0,"created":"2026-02-23"}]},"nuclei":[{"id":"CVE-2021-20038","name":"SonicWall SMA100 Stack - Buffer Overflow/Remote Code Execution","severity":"critical","path":"http/cves/2021/CVE-2021-20038.yaml","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-20038.yaml"}],"first":{"date":"2022-01-11","source":"PoC-in-GitHub","url":"https://github.com/jbaines-r7/badblood"},"provenance":"source"},"exploitRefs":["https://github.com/jbaines-r7/badblood","https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/"],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2021-12-08","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-20038","provenance":"source"},{"date":"2022-01-11","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/jbaines-r7/badblood","provenance":"source"},{"date":"2022-01-28","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","provenance":"source"},{"date":"2022-01-28","kind":"kev","label":"Added to CISA KEV (known ransomware use)","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2022-01-28","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-7501","provenance":"source"}],"speed":{"daysToPublicExploit":34,"firstExploitFrom":"PoC-in-GitHub","daysToKev":51},"priority":{"score":79.9,"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 1735 days ago"},{"name":"Known ransomware use","points":10.0,"detail":"CISA KEV and VulnCheck KEV: Known"},{"name":"EPSS percentile","points":19.99,"detail":"percentile 0.9997"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"2 NVD references tagged Exploit; 3 PoC-in-GitHub repos; 1 nuclei template"},{"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"}]}}