{"id":"CVE-2021-35247","published":"2022-01-10T14:10:17Z","modified":"2026-06-17T03:57:22Z","title":"SolarWinds Serv-U Improper Input Validation Vulnerability","vendor":"SolarWinds","product":"Serv-U","tier":"core","eol":null,"description":{"text":"Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized. SolarWinds has updated the input mechanism to perform additional validation and sanitization. Please Note: No downstream affect has been detected as the LDAP servers ignored improper characters. To insure proper input validation is completed in all environments. SolarWinds recommends scheduling an update to the latest version of Serv-U.","provenance":"source","from":"NVD"},"summary":{"text":"SolarWinds Serv-U contains an improper input validation flaw in its web login screen's LDAP authentication path, where characters were not sufficiently sanitized before being passed on. An attacker with network access can send crafted login input without needing authentication or user interaction, which may result in limited integrity impact, though the vendor reports no downstream effect was detected because the LDAP servers ignored the improper characters.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:14:31Z"},"cvss":{"score":5.3,"severity":"MEDIUM","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","provenance":"source","from":"NVD"},"epss":{"score":0.03453,"percentile":0.88988,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2022-01-21","dueDate":"2022-02-04","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-35247","provenance":"source"},"vulncheckKev":{"dateAdded":"2022-01-19","exploitedFirstSeen":"2022-01-19","ransomware":false,"evidence":[{"url":"https://www.microsoft.com/en-us/security/blog/2021/12/11/guidance-for-preventing-detecting-and-hunting-for-cve-2021-44228-log4j-2-exploitation/","date":"2022-01-19"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2022-01-21"},{"url":"https://www.mandiant.com/resources/blog/zero-days-exploited-2022","date":"2023-03-20"}],"evidenceTotal":3,"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-20","name":"Improper Input Validation"}],"references":[{"url":"https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htm","tags":["Release Notes","Vendor Advisory"]},{"url":"https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247","tags":["Broken Link","Vendor Advisory"]},{"url":"https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htm","tags":["Release Notes","Vendor Advisory"]},{"url":"https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247","tags":["Broken Link","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35247","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: Unauthenticated input on public-facing web login","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized","start":0,"end":107}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-21890","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-21890","exploited":true,"exploitedSince":"2022-01-21","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"}],"timeline":[{"date":"2022-01-10","kind":"published","label":"Published 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use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":17.8,"detail":"percentile 0.8899"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":3.71,"detail":"base score 5.3"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}