Reflected cross-site scripting issue in Datasette

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N · score source

EPSS

• CVE-2021-32670: 0.96% estimated exploitation activity in the next 30 days; percentile 61.58 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The `?_trace=1` debugging feature in Datasette does not correctly escape generated HTML, resulting in a reflected cross-site scripting vulnerability. This vulnerability is particularly relevant if your Datasette installation includes authenticated features using plugins such as 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 - Datasette issue #1360

For more…

Published by the source

7 Jun 2021, 21:47 UTC

Last modified by the source

8 Jul 2026, 06:28 UTC

Source last checked

25 Oct 2026, 04:53 UTC

1. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xw7c-jx9m-xh5g

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# Patch Next advisory brief: CVE-2021-32670

Advisory: Reflected cross-site scripting issue in Datasette
IDs: CVE-2021-32670, GHSA-xw7c-jx9m-xh5g
Record: https://patchnext.com/advisories/cve-2021-32670 (revision 2, source checked 25 Oct 2026, 04:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: datasette 0.56.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI datasette: affected < 0.56.1; fixed in 0.56.1

## Suggested inspection (read-only)
- `python -m pip show datasette`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on datasette.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-xw7c-jx9m-xh5g (OSV record GHSA-xw7c-jx9m-xh5g lists affected ranges: PyPI datasette >=0 <0.56.1 (fixed))

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