# CVE-2021-33926: Server-Side Request Forgery in Plone CMS

> Attackers can access sensitive information via the RSS feed portlet in Plone CMS, requiring an upgrade to mitigate.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Feb 2023
- **Updated:** 19 Mar 2025
- **Also known as:** GHSA-47p5-p3jw-w78w, PYSEC-2023-289

## What is CVE-2021-33926?

CVE-2021-33926 is a high-severity server-side request forgery vulnerability in Plone Plone, published on 17 Feb 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An issue in Plone CMS v. 5.2.4, 5.2.3, 5.2.2, 5.2.1, 5.2.0, 5.1rc2, 5.1rc1, 5.1b4, 5.1b3, 5.1b2, 5.1a2, 5.1a1, 5.1.7, 5.1.6, 5.1.5, 5.1.4, 5.1.2, 5.1.1 5.1, 5.0rc3, 5.0rc2, 5.0rc1, 5.0.9, 5.0.8, 5.0.7, 5.0.6, 5.0.5, 5.0.4, 5.0.3, 5.0.2, 5.0.10, 5.0.1, 5.0, 4.3.9, 4.3.8, 4.3.7, 4.3.6, 4.3.5, 4.3.4, 4.3.3, 4.3.20, 4 allows attacker to access sensitive information via the RSS feed protlet.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2021-33926?

3 open source packages ship an affected version, including plone and Plone. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `plone` | PyPI | From 4.3 | 5.2.5 |
| `plone` | PyPI | From 4.3 | 5.2.5 |
| `Plone` | PyPI | From 4.3 | 5.2.5 |

Products: Plone Plone.

## How do I fix CVE-2021-33926?

Upgrade plone to 5.2.5 or later.

## Is CVE-2021-33926 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-33926 exists.

## Other vulnerabilities in Plone Plone

- [CVE-2021-33509](https://insights.sbomify.com/CVE-2021-33509/): Incorrect Permission Assignment for Critical Resource in Plone (critical 9.9)
- [CVE-2020-35190](https://insights.sbomify.com/CVE-2020-35190/): Hardcoded credentials in n/a (critical 9.8)
- [CVE-2020-7941](https://insights.sbomify.com/CVE-2020-7941/): Plone Unauthenticated Write Vulnerability (critical 9.8)
- [CVE-2011-3587](https://insights.sbomify.com/CVE-2011-3587/): Zope Command Execution Vulnerability (critical 9.3)
- [CVE-2020-28734](https://insights.sbomify.com/CVE-2020-28734/): Improper Restriction of XML External Entity Reference in Plone (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33926 and fix it if it is affected.

What it is: CVE-2021-33926 is a high-severity server-side request forgery vulnerability in Plone Plone, published on 17 Feb 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-33926 exists.

Affected packages and fixed versions:
- plone (PyPI): affected from 4.3; fixed in 5.2.5
- plone (PyPI): affected from 4.3; fixed in 5.2.5
- Plone (PyPI): affected from 4.3; fixed in 5.2.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-33926/ (Markdown: https://insights.sbomify.com/CVE-2021-33926/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33926
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33926
- OSV: https://osv.dev/vulnerability/CVE-2021-33926

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33926/
Summaries are generated and may contain mistakes; the official description above is the record.