Affected: Mozilla Bleach

In Mozilla Bleach before 3.11, a mutation XSS affects users calling bleach.clean with noscript and a raw tag in the allowed/whitelisted tags option.

Affected: PyPI: bleach

### 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)

Affected: PyPI: bleach

In Mozilla Bleach before 3.11, a mutation XSS affects users calling bleach.clean with noscript and a raw tag in the allowed/whitelisted tags option.