{"id":"CVE-2021-27671","aliases":["EUVD-2021-1936","GHSA-xmr7-v725-2jjr","RUSTSEC-2021-0026"],"status":"published","title":"Cross site scripting in comrak","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","severity":{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.00686,"percentile":0.52978,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-79"],"published":"2021-02-21T12:00:00Z","modified":"2026-10-24T10:30:59Z","fixes":[{"ecosystem":"crates.io","package":"comrak","fixed_in":["0.9.1"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"crates.io","package":"comrak","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.9.1"}]}]},{"source":"osv","ecosystem":"crates.io","package":"comrak","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.9.1"}]}]},{"source":"osv","ecosystem":"crates.io","package":"comrak","ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"0.9.1"}]}]}],"products":[{"vendor":"comrak_project","product":"comrak"}],"references":[{"url":"https://rustsec.org/advisories/RUSTSEC-2021-0026.html","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27671","tags":["advisory"]},{"url":"https://github.com/kivikakk/comrak/releases/tag/0.9.1","tags":["web"]},{"url":"https://github.com/kivikakk/comrak/commit/b3efbb6e427bcd33bb14db45753ad4fd98e0f5bf","tags":["web"]},{"url":"https://github.com/advisories/GHSA-xmr7-v725-2jjr"},{"url":"https://github.com/kivikakk/comrak","tags":["package"]},{"url":"https://crates.io/crates/comrak","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2021-27671","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","status":"published","published":"2021-02-25T00:33:48Z","modified":"2024-08-03T21:26:10.659Z","updated_at":"2026-11-02T14:33:04.360272Z"}],"euvd":[{"id":"EUVD-2021-1936","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","status":"published","published":"2021-02-25T00:33:48Z","modified":"2024-08-03T21:26:10Z","updated_at":"2026-11-03T03:24:48.366655Z"}],"ghsa":[{"id":"GHSA-xmr7-v725-2jjr","title":"Cross site scripting in comrak","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. Cross site scripting (XSS) can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","status":"published","published":"2021-08-25T20:52:12Z","modified":"2023-03-22T20:54:48Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:36:48.041653Z"}],"nvd":[{"id":"CVE-2021-27671","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","status":"published","published":"2021-02-25T01:15:13.243Z","modified":"2026-06-17T03:45:19.75Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"primary"},{"version":"2.0","score":4.3,"vector":"AV:N/AC:M/Au:N/C:N/I:P/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:06:50.399901Z"}],"osv":[{"id":"CVE-2021-27671","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","status":"published","published":"2021-02-25T01:15:13.243Z","modified":"2026-10-24T10:30:59.975948696Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:44:19.129331Z"},{"id":"GHSA-xmr7-v725-2jjr","title":"Cross site scripting in comrak","description":"An issue was discovered in the comrak crate before 0.9.1 for Rust. Cross site scripting (XSS) can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.","status":"published","published":"2021-08-25T20:52:12Z","modified":"2023-11-08T04:05:25.341735Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:47:00.198893Z"},{"id":"RUSTSEC-2021-0026","title":"XSS in `comrak`","description":"The [comrak](https://github.com/kivikakk/comrak) we were matching unsafe URL prefixes, such as `data:` or `javascript:` , in a case-sensitive manner. This meant prefixes like `Data:` were untouched.","status":"published","published":"2021-02-21T12:00:00Z","modified":"2023-11-08T04:05:25.341735Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:53:39.492624Z"}]}}