CVE-2021-21359
Denial of Service in Page Error Handling
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
5.9
Denial of Service in Page Error Handling
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.
- Record
CVE-2021-21359- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-674, CWE-405
- Updated
- 2026-11-02
EUVDEUVD-2021-0598
5.9
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.
- Record
EUVD-2021-0598- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-4p9g-qgx9-397p
5.5
Denial of Service in Page Error Handling
Meta
- CVSS:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C(5.5)- CWE-405, CWE-674
- Status: DRAFT
Problem
Requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded.
Solution
Update to TYPO3 versions 9.5.25, 10.4.14, 11.1.1 that fix the problem described.
Credits
Thanks to Paul Keller, Mathias Bolt Lesniak and Kay Strobach who reported this issue and to TYPO3 framework merger Frank Nägler and to TYPO3 security team member Torben Hansen who fixed the issue.
References
- Record
GHSA-4p9g-qgx9-397p- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C - Weakness
- CWE-405, CWE-674
- Updated
- 2026-11-02
NVD
5.9
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.
- Record
CVE-2021-21359- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-405, CWE-674
- Updated
- 2026-11-02
OSV
7.5
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.
- Record
CVE-2021-21359- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVGHSA-4p9g-qgx9-397p
5.9
Denial of Service in Page Error Handling
Meta
- CVSS:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C(5.5)- CWE-405, CWE-674
- Status: DRAFT
Problem
Requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded.
Solution
Update to TYPO3 versions 9.5.25, 10.4.14, 11.1.1 that fix the problem described.
Credits
Thanks to Paul Keller, Mathias Bolt Lesniak and Kay Strobach who reported this issue and to TYPO3 framework merger Frank Nägler and to TYPO3 security team member Torben Hansen who fixed the issue.
References
- Record
GHSA-4p9g-qgx9-397p- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C - Weakness
- CWE-405, CWE-674
- Updated
- 2026-11-02
OSVBIT-typo3-2021-21359 No score
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.25, 10.4.14, 11.1.1 requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This is fixed in versions 9.5.25, 10.4.14, 11.1.1.
- Record
BIT-typo3-2021-21359- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
typo3/cms-corePackagist |
10.0.0 up to 10.4.14 | 10.4.14 |
typo3/cms-corePackagist |
11.0.0 up to 11.1.1 | 11.1.1 |
typo3/cms-corePackagist |
9.0.0 up to 9.5.25 | 9.5.25 |
typo3/cmsPackagist |
10.0.0 up to 10.4.14 | 10.4.14 |
typo3/cmsPackagist |
11.0.0 up to 11.1.1 | 11.1.1 |
typo3/cmsPackagist |
9.0.0 up to 9.5.25 | 9.5.25 |
typo3Bitnami |
9.0.0 up to 9.5.25, 10.0.0 up to 10.4.14, 11.0.0 up to 11.1.1 | 9.5.2510.4.1411.1.1 |
typo3/cms-corePackagist |
10.0.0 up to 10.4.14, plus listed versions v10.0.0v10.1.0v10.2.0v10.2.1v10.2.2 Show 15 moreShow lessv10.3.0v10.4.0v10.4.1v10.4.10v10.4.11v10.4.12v10.4.13v10.4.2v10.4.3v10.4.4v10.4.5v10.4.6v10.4.7v10.4.8v10.4.9 |
10.4.14 |
typo3/cms-corePackagist |
11.0.0 up to 11.1.1, plus listed versions v11.0.0v11.1.0 |
11.1.1 |
typo3/cms-corePackagist |
9.0.0 up to 9.5.25, plus listed versions v9.0.0v9.1.0v9.2.0v9.2.1v9.3.0 Show 29 moreShow lessv9.3.1v9.3.2v9.3.3v9.4.0v9.5.0v9.5.1v9.5.10v9.5.11v9.5.12v9.5.13v9.5.14v9.5.15v9.5.16v9.5.17v9.5.18v9.5.19v9.5.2v9.5.20v9.5.21v9.5.22v9.5.23v9.5.24v9.5.3v9.5.4v9.5.5v9.5.6v9.5.7v9.5.8v9.5.9 |
9.5.25 |
typo3/cmsPackagist |
10.0.0 up to 10.4.14, plus listed versions v10.0.0v10.1.0v10.2.0v10.2.1v10.2.2 Show 15 moreShow lessv10.3.0v10.4.0v10.4.1v10.4.10v10.4.11v10.4.12v10.4.13v10.4.2v10.4.3v10.4.4v10.4.5v10.4.6v10.4.7v10.4.8v10.4.9 |
10.4.14 |
typo3/cmsPackagist |
11.0.0 up to 11.1.1, plus listed versions v11.0.0v11.1.0 |
11.1.1 |
typo3/cmsPackagist |
9.0.0 up to 9.5.25, plus listed versions v9.0.0v9.1.0v9.2.0v9.2.1v9.3.0 Show 29 moreShow lessv9.3.1v9.3.2v9.3.3v9.4.0v9.5.0v9.5.1v9.5.10v9.5.11v9.5.12v9.5.13v9.5.14v9.5.15v9.5.16v9.5.17v9.5.18v9.5.19v9.5.2v9.5.20v9.5.21v9.5.22v9.5.23v9.5.24v9.5.3v9.5.4v9.5.5v9.5.6v9.5.7v9.5.8v9.5.9 |
9.5.25 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21359 is a medium vulnerability (CVSS 5.9) in Typo3, published March 23, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.73%, the 77th percentile. Fixed in typo3/cms-core 10.4.14.
References
packagist.org/packages/typo3/cms-core
github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-4p9g-qgx9-397p
typo3.org/security/advisory/typo3-core-sa-2021-005
nvd.nist.gov/vuln/detail/CVE-2021-21359
github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms-core/CVE-2021-21359.yaml
github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms/CVE-2021-21359.yaml
github.com/advisories/GHSA-4p9g-qgx9-397p