CVE-2020-28734 json
Improper Restriction of XML External Entity Reference in Plone
published 2020-12-30 5 y ago modified 2026-07-13 3 mo ago also GHSA-wq6x-g685-w5f2 , PYSEC-2020-246 , PYSEC-2026-2880 , PYSEC-2026-2883 , PYSEC-2026-2886 , PYSEC-2026-736 , EUVD-2020-0140
- cvss
- 8.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.5%
- EPSS 1.5% chance of exploitation in 30 days, percentile 73%
- public exploits
- 0
- none known
Summary
Plone before 5.2.3 allows XXE attacks via a feature that is explicitly only available to the Manager role.
Patch / fix
- pypi plone 5.2.3
- pypi plone-app-event 3.2.10
- pypi plone-app-theming 4.1.6
- pypi plone-app-dexterity 2.6.8
- pypi plone-supermodel 1.6.3
- plone plone 5.2.3
Exploit prediction
1.45% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 6.5 | AV:N/AC:L/Au:S/C:P/I:P/A:P |
| GitHub | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| OSV | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | plone | <5.2.3 |
5.2.3 |
| pypi | plone-app-event | <3.2.10 |
3.2.10 |
| pypi | plone-app-theming | <4.1.6 |
4.1.6 |
| pypi | plone-app-dexterity | <2.6.8 |
2.6.8 |
| pypi | plone-supermodel | <1.6.3 |
1.6.3 |
Classification
- Weakness
-
- CWE-611 Improper Restriction of XML External Entity Reference
References
-
github.com
/plone/Products.CMFPlone/issues/3209
web, patch, third-party-advisory, report
-
dist.plone.org
/release/5.2.3/RELEASE-NOTES.txt
web, release-notes, vendor-advisory
-
misakikata.com
/codes/plone/python-en.html
web, broken-link
-
nvd.nist.gov
/vuln/detail/CVE-2020-28734
advisory
-
github.com
/advisories/GHSA-wq6x-g685-w5f2
advisory
-
github.com
/pypa/advisory-database/tree/main/vulns/plone/PYSEC-2020-246.yaml
web
-
pypi.org
/project/plone-supermodel
package
-
pypi.org
/project/plone-app-event
package
-
pypi.org
/project/plone-app-dexterity
package
-
pypi.org
/project/plone-app-theming
package
Sources
- CVE List CVE-2020-28734
- GitHub Advisory GHSA-wq6x-g685-w5f2
- NVD CVE-2020-28734
- OSV PYSEC-2026-736
- OSV PYSEC-2026-2883
- OSV PYSEC-2026-2880
- OSV PYSEC-2020-246
- OSV PYSEC-2026-2886
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.