CVE-2021-39286 json
Cross-site scripting in pywb
published 2021-08-18 5 y ago modified 2026-06-17 4 mo ago also GHSA-947x-pv47-pp3q , PYSEC-2021-120 , EUVD-2021-0213
- cvss
- 6.1
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 53%
- public exploits
- 0
- none known
Summary
Webrecorder pywb before 2.6.0 allows XSS because it does not ensure that Jinja2 templates are autoescaped.
Patch / fix
Exploit prediction
0.70% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:P/A:N |
| GitHub | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | pywb | <2.6.0 |
2.6.0 |
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/webrecorder/pywb/commit/f7bd84cdacdd665ff73ae8d09a202f60be2ebae9
web, patch, third-party-advisory
-
github.com
/webrecorder/pywb/compare/v-2.5.0...v-2.6.0
web, release-notes, third-party-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-39286
advisory
-
github.com
/advisories/GHSA-947x-pv47-pp3q
advisory
-
github.com
/pypa/advisory-database/tree/main/vulns/pywb/PYSEC-2021-120.yaml
web
-
github.com
/webrecorder/pywb
package
Sources
- CVE List CVE-2021-39286
- GitHub Advisory GHSA-947x-pv47-pp3q
- NVD CVE-2021-39286
- OSV PYSEC-2021-120
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.