{"id":"CVE-2021-33766","title":"Microsoft Exchange Server Information Disclosure Vulnerability","summary":"Microsoft Exchange Server Information Disclosure Vulnerability","severity":"high","cvss":7.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","vendor":"microsoft","product":"exchange_server","affected":["exchange_server = 2013","exchange_server = 2016","exchange_server = 2019"],"published":"2021-07-14","updated":"2026-08-10","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-33766","references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766","label":"secure@microsoft.com"},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-798/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","kev","in-the-wild","exploit-available"],"epss":0.98136,"epssPercentile":0.99912,"kev":true,"kevDateAdded":"2022-01-18","kevDueDate":"2022-02-01","kevRansomware":false,"exploited":true,"zeroDay":true,"ingestedAt":"2026-08-10T16:41:15.440Z","exploits":{"github":2,"githubRepos":["https://github.com/bhdresh/CVE-2021-33766","https://github.com/demossl/CVE-2021-33766-ProxyToken"],"nuclei":["CVE-2021-33766"],"checkedAt":"2026-09-24T07:52:48.016Z"},"exploitAvailable":true,"slug":"CVE-2021-33766","body":"## Overview\n\nMicrosoft Exchange Server Information Disclosure Vulnerability\n\n## Affected\n\n- `exchange_server = 2013`\n- `exchange_server = 2016`\n- `exchange_server = 2019`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"abyssal","depthScore":85,"depthScoreParts":{"impact":40.2,"likelihood":19.6,"exploitation":25,"ransomware":0},"changes":[{"seq":4522,"id":"CVE-2021-33766","ts":1788887187472,"field":"exploit_available","old":"false","new":"true"},{"seq":3405,"id":"CVE-2021-33766","ts":1788886305156,"field":"exploit_available","old":"true","new":"false"},{"seq":2260,"id":"CVE-2021-33766","ts":1788882974655,"field":"exploit_available","old":"false","new":"true"},{"seq":1289,"id":"CVE-2021-33766","ts":1788882386455,"field":"exploit_available","old":"true","new":"false"},{"seq":403,"id":"CVE-2021-33766","ts":1788881822165,"field":"exploit_available","old":"false","new":"true"}]}