CVE-2021-33926Public exploitNetwork attack vector

Authenticated internal resource access via unrestricted feed URL

Published Feb 17, 2023 · Updated Mar 19, 2025

SSRF in the RSS feed portlet in Plone CMS 4.3 through 5.2.4 allows remote authenticated users to access internal resources via crafted feed URLs. The portlet passes its configured feed location to feedparser without restricting the URL to HTTP or HTTPS, causing the server to retrieve an attacker-selected internal resource. Access to RSS portlet configuration is required, and the blind request can expose information reachable from the Plone server.

CVSS severity8.8
High
EPSS probability1.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in the RSS feed portlet in Plone CMS 4.3 through 5.2.4 allows remote authenticated users to access internal resources via crafted feed URLs. The portlet passes its configured feed location to feedparser without restricting the URL to HTTP or HTTPS, causing the server to retrieve an attacker-selected internal resource. Access to RSS portlet configuration is required, and the blind request can expose information reachable from the Plone server.

The record

CVE
CVE-2021-33926
Published
Feb 17, 2023
Updated
Mar 19, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-918, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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