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Not in CISA KEV
HIGH severity

CVE-2020-28735 — plone

HIGH

CVE-2020-28735 is a high-severity (CVSS 8.8) Server-Side Request Forgery (SSRF) vulnerability in plone. A fix is available for plone — see the affected versions and patch details below.

SSRF attacks via tracebacks in Plone

Also known asGHSA-x7wf-5mjc-6x76PYSEC-2020-247PYSEC-2026-2881PYSEC-2026-2884PYSEC-2026-2887PYSEC-2026-737
Published
Updated
Affected
5 pkgs
Patched
5 / 5
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs73th percentile — riskier than 73% of all scored CVEsHighest risk
0.00%0.65%1.30%1.95%0.5%1.5%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-28735 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

5 pkgs affected
🐍plone🐍plone-app-event🐍plone-app-theming🐍plone-app-dexterity🐍plone-supermodel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

5 total 5 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIploneall versions5.2.3pip install --upgrade 'plone==5.2.3'
🐍PyPIplone-app-eventall versions3.2.10pip install --upgrade 'plone-app-event==3.2.10'
🐍PyPIplone-app-themingall versions4.1.6pip install --upgrade 'plone-app-theming==4.1.6'
🐍PyPIplone-app-dexterityall versions2.6.8pip install --upgrade 'plone-app-dexterity==2.6.8'
🐍PyPIplone-supermodelall versions1.6.3pip install --upgrade 'plone-supermodel==1.6.3'

Affected Products

1 product · 1 configurations
Application
ploneplone
< 5.2.3
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plone, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update plone to 5.2.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-28735 is resolved across your whole dependency graph.

  3. Workarounds

    Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Frequently Asked Questions

Plone before 5.2.3 allows SSRF attacks via the tracebacks feature (only available to the Manager role).
O3 Security · Impact-Aware SCA

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CVE-2020-28735: plone SSRF — Fixed in 5.2.3