{"api_version":"1","generated_at":"2026-07-23T12:18:48+00:00","cve":"CVE-2021-43802","urls":{"html":"https://cve.report/CVE-2021-43802","api":"https://cve.report/api/cve/CVE-2021-43802.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2021-43802","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-43802"},"summary":{"title":"CVE-2021-43802","description":"Etherpad is a real-time collaborative editor. In versions prior to 1.8.16, an attacker can craft an `*.etherpad` file that, when imported, might allow the attacker to gain admin privileges for the Etherpad instance. This, in turn, can be used to install a malicious Etherpad plugin that can execute arbitrary code (including system commands). To gain privileges, the attacker must be able to trigger deletion of `express-session` state or wait for old `express-session` state to be cleaned up. Core Etherpad does not delete any `express-session` state, so the only known attacks require either a plugin that can delete session state or a custom cleanup process (such as a cron job that deletes old `sessionstorage:*` records). The problem has been fixed in version 1.8.16. If users cannot upgrade to 1.8.16 or install patches manually, several workarounds are available. Users may configure their reverse proxies to reject requests to `/p/*/import`, which will block all imports, not just `*.etherpad` imports; limit all users to read-only access; and/or prevent the reuse of `express_sid` cookie values that refer to deleted express-session state. More detailed information and general mitigation strategies may be found in the GitHub Security Advisory.","state":"PUBLIC","assigner":"security-advisories@github.com","published_at":"2021-12-09 23:15:00","updated_at":"2023-08-31 16:19:00"},"problem_types":["CWE-20","NVD-CWE-Other"],"metrics":[],"references":[{"url":"https://github.com/ether/etherpad-lite/releases/tag/1.8.16","name":"https://github.com/ether/etherpad-lite/releases/tag/1.8.16","refsource":"MISC","tags":[],"title":"Release 1.8.16 · ether/etherpad-lite · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://github.com/ether/etherpad-lite/security/advisories/GHSA-w3g3-qf3g-2mqc","name":"https://github.com/ether/etherpad-lite/security/advisories/GHSA-w3g3-qf3g-2mqc","refsource":"CONFIRM","tags":[],"title":"Admin privilege escalation and arbitrary code execution via malicious *.etherpad imports · Advisory · ether/etherpad-lite · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://github.com/ether/etherpad-lite/issues/5010","name":"https://github.com/ether/etherpad-lite/issues/5010","refsource":"MISC","tags":[],"title":"Sessionstorage is constantly growing · Issue #5010 · ether/etherpad-lite · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6f036456...77bcb507b30e762e9375b0511b3763e0162aae53","name":"https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6f036456...77bcb507b30e762e9375b0511b3763e0162aae53","refsource":"MISC","tags":[],"title":"Comparing b7065eb9a0ec7c3c265f8cfeb2534efe6f036456...77bcb507b30e762e9375b0511b3763e0162aae53 · ether/etherpad-lite · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-43802","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-43802","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2021","cve_id":"43802","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"etherpad","cpe5":"etherpad","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"CVE_data_meta":{"ASSIGNER":"security-advisories@github.com","ID":"CVE-2021-43802","STATE":"PUBLIC","TITLE":"Admin privilege escalation and arbitrary code execution via malicious *.etherpad imports"},"affects":{"vendor":{"vendor_data":[{"product":{"product_data":[{"product_name":"etherpad-lite","version":{"version_data":[{"version_value":"< 1.8.16"}]}}]},"vendor_name":"ether"}]}},"data_format":"MITRE","data_type":"CVE","data_version":"4.0","description":{"description_data":[{"lang":"eng","value":"Etherpad is a real-time collaborative editor. In versions prior to 1.8.16, an attacker can craft an `*.etherpad` file that, when imported, might allow the attacker to gain admin privileges for the Etherpad instance. This, in turn, can be used to install a malicious Etherpad plugin that can execute arbitrary code (including system commands). To gain privileges, the attacker must be able to trigger deletion of `express-session` state or wait for old `express-session` state to be cleaned up. Core Etherpad does not delete any `express-session` state, so the only known attacks require either a plugin that can delete session state or a custom cleanup process (such as a cron job that deletes old `sessionstorage:*` records). The problem has been fixed in version 1.8.16. If users cannot upgrade to 1.8.16 or install patches manually, several workarounds are available. Users may configure their reverse proxies to reject requests to `/p/*/import`, which will block all imports, not just `*.etherpad` imports; limit all users to read-only access; and/or prevent the reuse of `express_sid` cookie values that refer to deleted express-session state. More detailed information and general mitigation strategies may be found in the GitHub Security Advisory."}]},"impact":{"cvss":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":9.9,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"}},"problemtype":{"problemtype_data":[{"description":[{"lang":"eng","value":"CWE-790: Improper Filtering of Special Elements"}]},{"description":[{"lang":"eng","value":"CWE-1287: Improper Validation of Specified Type of Input"}]}]},"references":{"reference_data":[{"name":"https://github.com/ether/etherpad-lite/security/advisories/GHSA-w3g3-qf3g-2mqc","refsource":"CONFIRM","url":"https://github.com/ether/etherpad-lite/security/advisories/GHSA-w3g3-qf3g-2mqc"},{"name":"https://github.com/ether/etherpad-lite/issues/5010","refsource":"MISC","url":"https://github.com/ether/etherpad-lite/issues/5010"},{"name":"https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6f036456...77bcb507b30e762e9375b0511b3763e0162aae53","refsource":"MISC","url":"https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6f036456...77bcb507b30e762e9375b0511b3763e0162aae53"},{"name":"https://github.com/ether/etherpad-lite/releases/tag/1.8.16","refsource":"MISC","url":"https://github.com/ether/etherpad-lite/releases/tag/1.8.16"}]},"source":{"advisory":"GHSA-w3g3-qf3g-2mqc","discovery":"UNKNOWN"}},"nvd":{"publishedDate":"2021-12-09 23:15:00","lastModifiedDate":"2023-08-31 16:19:00","problem_types":["CWE-20","NVD-CWE-Other"],"metrics":{"baseMetricV3":{"cvssV3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH","baseScore":8.8,"baseSeverity":"HIGH"},"exploitabilityScore":2.8,"impactScore":5.9},"baseMetricV2":{"cvssV2":{"version":"2.0","vectorString":"AV:N/AC:L/Au:S/C:C/I:C/A:C","accessVector":"NETWORK","accessComplexity":"LOW","authentication":"SINGLE","confidentialityImpact":"COMPLETE","integrityImpact":"COMPLETE","availabilityImpact":"COMPLETE","baseScore":9},"severity":"HIGH","exploitabilityScore":8,"impactScore":10,"acInsufInfo":false,"obtainAllPrivilege":false,"obtainUserPrivilege":false,"obtainOtherPrivilege":false,"userInteractionRequired":false}},"configurations":{"CVE_data_version":"4.0","nodes":[{"operator":"OR","children":[],"cpe_match":[{"vulnerable":true,"cpe23Uri":"cpe:2.3:a:etherpad:etherpad:*:*:*:*:*:*:*:*","versionEndExcluding":"1.8.16","cpe_name":[]}]}]}},"legacy_mitre":{"record":{"CveYear":"2021","CveId":"43802","Ordinal":"221360","Title":"CVE-2021-43802","CVE":"CVE-2021-43802","Year":"2021"},"notes":[{"CveYear":"2021","CveId":"43802","Ordinal":"1","NoteData":"** RESERVED ** This candidate has been reserved by an organization or individual that will use it when announcing a new security problem. When the candidate has been publicized, the details for this candidate will be provided.","Type":"Description","Title":null}]}}}