- Component Type: TYPO3 CMS
- Subcomponent: Page Error Handling (ext:core, ext:frontend)
- Release Date: March 16, 2021
- Vulnerability Type: Denial of Service
- Affected Versions: 9.0.0-9.5.24, 10.0.0-10.4.13, 11.0.0-11.1.0
- Severity: Medium
- Suggested 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
- References: CVE-2021-21359, CWE-405, CWE-674
Requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as an 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.
Update to TYPO3 versions 9.5.25, 10.4.14, 11.1.1 that fix the problem described.
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.
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