No exploitation reportedFix available

CVE-2020-28735

Q: Is CVE-2020-28735 actively exploited?

Active exploitation of CVE-2020-28735 has not been confirmed. Its EPSS score was 1.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-28735?

CVE-2020-28735 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2020-12-30
Fixed in5.2.3
WeaknessCWE-918

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Plone before 5.2.3 allows SSRF attacks via the tracebacks feature (only available to the Manager role).

Timeline

dates in UTC

2020-12-3019:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-28735?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-28735?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Plone

Branch	Affected	Fixed in	Source
5.2	< 5.2.3	5.2.3	NVD · OSV

plone-app-dexterity

Branch	Affected	Fixed in	Source
2.6	< 2.6.8	2.6.8	OSV

plone-app-event

Branch	Affected	Fixed in	Source
3.2	< 3.2.10	3.2.10	OSV

2 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Plone to 5.2.3

Advisories and patches

dist.plone.orgRelease Notes · Vendor Advisory
github.comPatch

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.06.5read 2026-10-23
NVDweakness (CWE)CWE-918read 2026-10-23
FIRST EPSSEPSS score1.5 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published: 2020-12-30
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-28735?

Plone before 5.2.3 allows SSRF attacks via the tracebacks feature (only available to the Manager role).

Is CVE-2020-28735 actively exploited?

Active exploitation of CVE-2020-28735 has not been confirmed. Its EPSS score was 1.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-28735?

CVE-2020-28735 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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