CVE-2020-6802: XSS
First published: Mon Feb 24 2020(Updated: )
### Impact A [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. ### Patches v3.1.1 ### Workarounds * modify `bleach.clean` calls to not whitelist `noscript` and one or more of the following raw tags: ``` title textarea script style noembed noframes iframe xmp ``` * 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. ### References * https://bugzilla.mozilla.org/show_bug.cgi?id=1615315 * https://cure53.de/fp170.pdf * https://nvd.nist.gov/vuln/detail/CVE-2020-6802 * https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach ### Credits * Reported by [Yaniv Nizry](https://twitter.com/ynizry) from the CxSCA AppSec group at Checkmarx ### For more information If you have any questions or comments about this advisory: * Open an issue at [https://github.com/mozilla/bleach/issues](https://github.com/mozilla/bleach/issues) * Email us at [security@mozilla.org](mailto:security@mozilla.org)
Credit: security@mozilla.org security@mozilla.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Mozilla Bleach | <3.1.1 | |
| Fedoraproject Fedora | =30 | |
| Fedoraproject Fedora | =31 | |
| Fedoraproject Fedora | =32 | |
| pip/bleach | <3.1.1 | 3.1.1 |
| Fedora | =30 | |
| Fedora | =31 | |
| Fedora | =32 |
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Reference Links
- https://advisory.checkmarx.net/advisory/CX-2020-4276
- https://github.com/mozilla/bleach/security/advisories/GHSA-q65m-pv3f-wr5r
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/72R4VFFHDRSQMNT7IZU3X2755ZP4HGNI/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OCNLM2MGQTOLCIVVYS2Z5S7KOQJR5JC4/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YTULPQB7HVPPYWEYVNHJGDTSPVIDHIZX/
- https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OCNLM2MGQTOLCIVVYS2Z5S7KOQJR5JC4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/72R4VFFHDRSQMNT7IZU3X2755ZP4HGNI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YTULPQB7HVPPYWEYVNHJGDTSPVIDHIZX/
- https://github.com/mozilla/bleach/commit/f77e0f6392177a06e46a49abd61a4d9f035e57fd
- https://bugzilla.mozilla.org/show_bug.cgi?id=1615315
- https://cure53.de/fp170.pdf
- https://nvd.nist.gov/vuln/detail/CVE-2020-6802
- https://github.com/pypa/advisory-database/tree/main/vulns/bleach/PYSEC-2020-27.yaml
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/72R4VFFHDRSQMNT7IZU3X2755ZP4HGNI
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OCNLM2MGQTOLCIVVYS2Z5S7KOQJR5JC4
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YTULPQB7HVPPYWEYVNHJGDTSPVIDHIZX
- https://github.com/advisories/GHSA-q65m-pv3f-wr5r (Advisory)
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