HOMEVULNERABILITIESCVE-2021-21359
HIGH

CVE-2021-21359

CWE-405Published: March 23, 2021· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-21359 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

typo31 product(s)
typo3
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-4p9g-qgx9-397p
ADVISORYhttps://packagist.org/packages/typo3/cms-core
ADVISORYhttps://typo3.org/security/advisory/typo3-core-sa-2021-005
ADVISORYhttps://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-4p9g-qgx9-397p
ADVISORYhttps://packagist.org/packages/typo3/cms-core
ADVISORYhttps://typo3.org/security/advisory/typo3-core-sa-2021-005

All References (6)

→
https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-4p9g-qgx9-397pThird Party Advisory
→
https://packagist.org/packages/typo3/cms-coreRelease Notes · Third Party Advisory
→
https://typo3.org/security/advisory/typo3-core-sa-2021-005Vendor Advisory
→
https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-4p9g-qgx9-397pThird Party Advisory
→
https://packagist.org/packages/typo3/cms-coreRelease Notes · Third Party Advisory
→
https://typo3.org/security/advisory/typo3-core-sa-2021-005Vendor Advisory

Quick Facts

CVE IDCVE-2021-21359
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-405
CISA KEVNo
Affected1 vendor(s)
PublishedMar 23, 2021

Related CVEs (CWE-405)

CVE-2025-53633
9.8
CVE-2025-8677
7.5
CVE-2025-31987
7.5
CVE-2024-39743
7.5
CVE-2018-15492
7.5
CVE-2019-11479
7.5

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-21359 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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