---
id: CVE-2021-32670
aliases:
  - GHSA-xw7c-jx9m-xh5g
  - GHSA-gff3-739c-gxfq
  - PYSEC-2021-89
title: Reflected cross-site scripting issue in Datasette
summary: Reflected cross-site scripting issue in Datasette
severity: high
cvss: 7.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N'
vendor: datasette
product: datasette
ecosystem: pip
affected:
  - datasette < 0.56.1
patched:
  - datasette 0.56.1
published: '2021-06-07'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-xw7c-jx9m-xh5g'
references:
  - url: >-
      https://github.com/simonw/datasette/security/advisories/GHSA-xw7c-jx9m-xh5g
  - url: 'https://github.com/simonw/datasette/issues/1360'
  - url: 'https://datasette.io/plugins/datasette-auth-passwords'
  - url: 'https://github.com/advisories/GHSA-gff3-739c-gxfq'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/datasette/PYSEC-2021-89.yaml
  - url: 'https://github.com/simonw/datasette'
  - url: 'https://owasp.org/www-community/attacks/xss/#reflected-xss-attacks'
  - url: 'https://pypi.org/project/datasette'
tags:
  - osv
  - pip
epss: 0.0096
epssPercentile: 0.59922
ingestedAt: '2026-07-08T18:25:54.697Z'
---

## Overview

### 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`


## Affected packages

- `datasette < 0.56.1`

## Remediation

Upgrade to a patched release:

- `datasette 0.56.1`