CVE-2021-3313

Name: CVE-2021-3313
Creator: NVD / NIST
Published: 2021-05-20T16:15:08.283+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.97%

Last modified Jun 17, 2026

CVE-2021-3313 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. Plone CMS until version 5.2.4 has a stored Cross-Site Scripting (XSS) vulnerability in the user fullname property and the file upload functionality. The user's input data is not properly encoded when being echoed back to the user. EPSS estimates a 0.97% chance of exploitation in the next 30 days.

Description

Plone CMS until version 5.2.4 has a stored Cross-Site Scripting (XSS) vulnerability in the user fullname property and the file upload functionality. The user's input data is not properly encoded when being echoed back to the user. This data can be interpreted as executable code by the browser and allows an attacker to execute JavaScript in the context of the victim's browser if the victim opens a vulnerable page containing an XSS payload.

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.97%

57.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Plone	Plone	< 5.2.4

References

http://www.openwall.com/lists/oss-security/2021/05/22/1Mailing List, Third Party Advisory
https://plone.org/download/releases/5.2.3Release Notes, Vendor Advisory
https://plone.org/security/hotfix/20210518Vendor Advisory
https://www.compass-security.com/fileadmin/Research/Advisories/2021-07_CSNC-2021-013_XSS_in_Plone_CMS.txtExploit, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/22/1Mailing List, Third Party Advisory
https://plone.org/download/releases/5.2.3Release Notes, Vendor Advisory
https://plone.org/security/hotfix/20210518Vendor Advisory
https://www.compass-security.com/fileadmin/Research/Advisories/2021-07_CSNC-2021-013_XSS_in_Plone_CMS.txtExploit, Third Party Advisory

Timeline

Published: May 20, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3313?

How severe is CVE-2021-3313?

CVE-2021-3313 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.97% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3313?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3313?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST