Reflected cross-site scripting issue in Datasette

### Impact The `?_trace=1` debugging feature in Datasette does not correctly escape generated HTML, resulting in a [reflected cross-site scripting](https://owasp.org/www-community/attacks/xss/#reflected-xss-attacks) vulnerability. This vulnerability is particularly relevant if your Datasette installation includes authenticated features using plugins such as [datasette-auth-passwords](https://datasette.io/plugins/datasette-auth-passwords) as an attacker could use the vulnerability to access protected data. ### Patches Datasette 0.57 and 0.56.1 both include patches for this issue. ### Workarounds If you run Datasette behind a proxy you can workaround this issue by rejecting any incoming requests with `?_trace=` or `&_trace=` in their query string parameters. ### References - [OWASP guide to reflected cross-site scripting](https://owasp.org/www-community/attacks/xss/#reflected-xss-attacks) - [Datasette issue #1360](https://github.com/simonw/datasette/issues/1360) ### For more information If you have any questions or comments about this advisory: * Open a discussion in [simonw/datasette](https://github.com/simonw/datasette/discussions) * Email us at `swillison+datasette @ gmail.com`

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Severity from

GitHub (reviewed advisory)

Weakness

CWE-79

Also known as

CVE-2021-32670, GHSA-gff3-739c-gxfq, PYSEC-2021-89

• github.com/simonw/datasette/security/advisories/GHSA-xw7c-jx9m-xh5g
• github.com/simonw/datasette/issues/1360
• datasette.io/plugins/datasette-auth-passwords
• github.com/advisories/GHSA-gff3-739c-gxfq
• github.com/pypa/advisory-database/tree/main/vulns/datasette/PYSEC-2021-89.yaml
• github.com/simonw/datasette
• owasp.org/www-community/attacks/xss/#reflected-xss-attacks
• pypi.org/project/datasette