{"id":"CVE-2020-6802","aliases":["GHSA-q65m-pv3f-wr5r","PYSEC-2020-27"],"title":"XSS in Bleach when noscript and raw tag whitelisted","summary":"XSS in Bleach when noscript and raw tag whitelisted","severity":"medium","cvss":6.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","vendor":"bleach","product":"bleach","ecosystem":"pip","affected":["bleach < 3.1.1"],"patched":["bleach 3.1.1"],"published":"2020-02-24","updated":"2026-07-08","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-q65m-pv3f-wr5r","references":[{"url":"https://github.com/mozilla/bleach/security/advisories/GHSA-q65m-pv3f-wr5r"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-6802"},{"url":"https://github.com/mozilla/bleach/commit/f77e0f6392177a06e46a49abd61a4d9f035e57fd"},{"url":"https://advisory.checkmarx.net/advisory/CX-2020-4276"},{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1615315"},{"url":"https://cure53.de/fp170.pdf"},{"url":"https://github.com/mozilla/bleach"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/bleach/PYSEC-2020-27.yaml"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/72R4VFFHDRSQMNT7IZU3X2755ZP4HGNI"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OCNLM2MGQTOLCIVVYS2Z5S7KOQJR5JC4"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YTULPQB7HVPPYWEYVNHJGDTSPVIDHIZX"},{"url":"https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach"}],"tags":["osv","pip"],"epss":0.01731,"epssPercentile":0.76606,"ingestedAt":"2026-07-08T18:25:52.106Z","slug":"CVE-2020-6802","body":"## Overview\n\n### Impact\n\nA [mutation XSS](https://cure53.de/fp170.pdf) affects users calling `bleach.clean` with `noscript` and a raw tag (see below) in the allowed/whitelisted tags option.\n\n### Patches\n\nv3.1.1\n\n### Workarounds\n\n* modify `bleach.clean` calls to not whitelist `noscript` and one or more of the following raw tags:\n\n```\ntitle\ntextarea\nscript\nstyle\nnoembed\nnoframes\niframe\nxmp\n```\n\n* A strong [Content-Security-Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP) without `unsafe-inline` and `unsafe-eval` [`script-src`s](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/script-src)) will also help mitigate the risk.\n\n### References\n\n* https://bugzilla.mozilla.org/show_bug.cgi?id=1615315\n* https://cure53.de/fp170.pdf\n* https://nvd.nist.gov/vuln/detail/CVE-2020-6802\n* https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach\n\n### Credits\n\n* Reported by [Yaniv Nizry](https://twitter.com/ynizry) from the CxSCA AppSec group at Checkmarx\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n* Open an issue at [https://github.com/mozilla/bleach/issues](https://github.com/mozilla/bleach/issues)\n* Email us at [security@mozilla.org](mailto:security@mozilla.org)\n\n\n## Affected packages\n\n- `bleach < 3.1.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `bleach 3.1.1`","depth":"sunlit","depthScore":34,"depthScoreParts":{"impact":33.6,"likelihood":0.3,"exploitation":0,"ransomware":0},"changes":[]}