CVE-2021-21365

Name: CVE-2021-21365
Creator: NVD / NIST
Published: 2021-04-27T20:15:08.713+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.94%

Last modified Jun 17, 2026

CVE-2021-21365 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. Bootstrap Package is a theme for TYPO3. It has been discovered that rendering content in the website frontend is vulnerable to cross-site scripting. EPSS estimates a 0.94% chance of exploitation in the next 30 days.

Description

Bootstrap Package is a theme for TYPO3. It has been discovered that rendering content in the website frontend is vulnerable to cross-site scripting. A valid backend user account is needed to exploit this vulnerability. Users of the extension, who have overwritten the affected templates with custom code must manually apply the security fix. Update to version 7.1.2, 8.0.8, 9.1.4, 10.0.10 or 11.0.3 of the Bootstrap Package that fix the problem described. Updated version are available from the TYPO3 extension manager, Packagist and at https://extensions.typo3.org/extension/download/bootstrap_package/.

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

0.94%

56.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Typo3	Typo3	< 7.1.2
Typo3	Typo3	>= 8.0.0, < 8.0.8
Typo3	Typo3	>= 9.0.0, < 9.0.4
Typo3	Typo3	>= 9.1.0, < 9.1.3
Typo3	Typo3	>= 10.0.0, < 10.0.10
Typo3	Typo3	>= 11.0.0, < 11.0.3

References

https://github.com/benjaminkott/bootstrap_package/commit/de3a568fc311d6712d9339643e51e8627c80530bPatch, Third Party Advisory
https://github.com/benjaminkott/bootstrap_package/security/advisories/GHSA-p48w-vf3c-rqjxExploit, Third Party Advisory
https://typo3.org/security/advisory/typo3-ext-sa-2021-007Exploit, Patch, Vendor Advisory
https://github.com/benjaminkott/bootstrap_package/commit/de3a568fc311d6712d9339643e51e8627c80530bPatch, Third Party Advisory
https://github.com/benjaminkott/bootstrap_package/security/advisories/GHSA-p48w-vf3c-rqjxExploit, Third Party Advisory
https://typo3.org/security/advisory/typo3-ext-sa-2021-007Exploit, Patch, Vendor Advisory

Timeline

Published: Apr 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21365?

How severe is CVE-2021-21365?

CVE-2021-21365 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.94% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21365?

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-2021-21365?

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

Scan your code now

Source: NVD / NIST