{"api_version":"1","generated_at":"2026-04-26T02:52:09+00:00","cve":"CVE-2021-41115","urls":{"html":"https://cve.report/CVE-2021-41115","api":"https://cve.report/api/cve/CVE-2021-41115.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2021-41115","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-41115"},"summary":{"title":"CVE-2021-41115","description":"Zulip is an open source team chat server. In affected versions Zulip allows organization administrators on a server to configure \"linkifiers\" that automatically create links from messages that users send, detected via arbitrary regular expressions. Malicious organization administrators could subject the server to a denial-of-service via regular expression complexity attacks; most simply, by configuring a quadratic-time regular expression in a linkifier, and sending messages that exploited it. A regular expression attempted to parse the user-provided regexes to verify that they were safe from ReDoS -- this was both insufficient, as well as _itself_ subject to ReDoS if the organization administrator entered a sufficiently complex invalid regex. Affected users should [upgrade to the just-released Zulip 4.7](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-to-a-release), or [`main`](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-from-a-git-repository).","state":"PUBLIC","assigner":"security-advisories@github.com","published_at":"2021-10-07 23:15:00","updated_at":"2023-07-17 15:18:00"},"problem_types":["CWE-1333"],"metrics":[],"references":[{"url":"https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781","name":"https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781","refsource":"MISC","tags":[],"title":"CVE-2021-41115: Use re2 for user-supplied linkifier patterns. · zulip/zulip@e2d303c · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg","name":"https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg","refsource":"CONFIRM","tags":[],"title":"Regular expression denial-of-service in linkifiers · Advisory · zulip/zulip · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/","name":"https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/","refsource":"MISC","tags":[],"title":"GitHub Security Lab | Securing the world’s software, together","mime":"text/html","httpstatus":"404","archivestatus":"404"},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-41115","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41115","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2021","cve_id":"41115","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"zulip","cpe5":"zulip","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-2021-41115","STATE":"PUBLIC","TITLE":"Regular expression denial-of-service in Zulip"},"affects":{"vendor":{"vendor_data":[{"product":{"product_data":[{"product_name":"zulip","version":{"version_data":[{"version_value":"< 4.7"}]}}]},"vendor_name":"zulip"}]}},"data_format":"MITRE","data_type":"CVE","data_version":"4.0","description":{"description_data":[{"lang":"eng","value":"Zulip is an open source team chat server. In affected versions Zulip allows organization administrators on a server to configure \"linkifiers\" that automatically create links from messages that users send, detected via arbitrary regular expressions. Malicious organization administrators could subject the server to a denial-of-service via regular expression complexity attacks; most simply, by configuring a quadratic-time regular expression in a linkifier, and sending messages that exploited it. A regular expression attempted to parse the user-provided regexes to verify that they were safe from ReDoS -- this was both insufficient, as well as _itself_ subject to ReDoS if the organization administrator entered a sufficiently complex invalid regex. Affected users should [upgrade to the just-released Zulip 4.7](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-to-a-release), or [`main`](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-from-a-git-repository)."}]},"impact":{"cvss":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}},"problemtype":{"problemtype_data":[{"description":[{"lang":"eng","value":"CWE-400: Uncontrolled Resource Consumption"}]},{"description":[{"lang":"eng","value":"CWE-1333: Inefficient Regular Expression Complexity"}]}]},"references":{"reference_data":[{"name":"https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg","refsource":"CONFIRM","url":"https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg"},{"name":"https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781","refsource":"MISC","url":"https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781"},{"name":"https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/","refsource":"MISC","url":"https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/"}]},"source":{"advisory":"GHSA-4h36-mqfq-42jg","discovery":"UNKNOWN"}},"nvd":{"publishedDate":"2021-10-07 23:15:00","lastModifiedDate":"2023-07-17 15:18:00","problem_types":["CWE-1333"],"metrics":{"baseMetricV3":{"cvssV3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH","baseScore":6.5,"baseSeverity":"MEDIUM"},"exploitabilityScore":2.8,"impactScore":3.6},"baseMetricV2":{"cvssV2":{"version":"2.0","vectorString":"AV:N/AC:L/Au:S/C:N/I:N/A:P","accessVector":"NETWORK","accessComplexity":"LOW","authentication":"SINGLE","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"PARTIAL","baseScore":4},"severity":"MEDIUM","exploitabilityScore":8,"impactScore":2.9,"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:zulip:zulip:*:*:*:*:*:*:*:*","versionEndExcluding":"4.7","cpe_name":[]}]}]}},"legacy_mitre":{"record":{"CveYear":"2021","CveId":"41115","Ordinal":"217046","Title":"CVE-2021-41115","CVE":"CVE-2021-41115","Year":"2021"},"notes":[{"CveYear":"2021","CveId":"41115","Ordinal":"1","NoteData":"Zulip is an open source team chat server. In affected versions Zulip allows organization administrators on a server to configure \"linkifiers\" that automatically create links from messages that users send, detected via arbitrary regular expressions. Malicious organization administrators could subject the server to a denial-of-service via regular expression complexity attacks; most simply, by configuring a quadratic-time regular expression in a linkifier, and sending messages that exploited it. A regular expression attempted to parse the user-provided regexes to verify that they were safe from ReDoS -- this was both insufficient, as well as _itself_ subject to ReDoS if the organization administrator entered a sufficiently complex invalid regex. Affected users should [upgrade to the just-released Zulip 4.7](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-to-a-release), or [`main`](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-from-a-git-repository).","Type":"Description","Title":null},{"CveYear":"2021","CveId":"41115","Ordinal":"2","NoteData":"2021-10-07","Type":"Other","Title":"Published"},{"CveYear":"2021","CveId":"41115","Ordinal":"3","NoteData":"2021-10-07","Type":"Other","Title":"Modified"}]}}}