Open Redirection in Login Handling

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2021-21338: 1.10% estimated exploitation activity in the next 30 days; percentile 65.80 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Problem It has been discovered that Login Handling is susceptible to open redirection which allows attackers redirecting to arbitrary content, and conducting phishing attacks. No authentication is required in order to exploit this vulnerability. Solution Update to TYPO3 versions 6.2.57, 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described. Credits Thanks to Alexander Kellner who reported this issue and to TYPO3 security team member Torben Hansen who fixed the issue. References TYPO3-CORE-SA-2021-001

Published by the source

23 Mar 2021, 01:53 UTC

Last modified by the source

1 Feb 2024, 19:01 UTC

Source last checked

26 Oct 2026, 14:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4jhw-2p6j-5wmp

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# Patch Next advisory brief: CVE-2021-21338

Advisory: Open Redirection in Login Handling
IDs: CVE-2021-21338, GHSA-4jhw-2p6j-5wmp
Record: https://patchnext.com/advisories/cve-2021-21338 (revision 1, source checked 26 Oct 2026, 14:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: typo3/cms-core 11.1.1, 10.4.14, 9.5.25, 8.7.40, 7.6.51, 6.2.57; typo3/cms 11.1.1, 10.4.14, 9.5.25. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist typo3/cms-core: affected >= 6.2.0, <= 6.2.56; >= 7.0.0, <= 7.6.50; >= 8.0.0, <= 8.7.39; >= 10.0.0, < 10.4.14; >= 11.0.0, < 11.1.1; >= 9.0.0, < 9.5.25; fixed in 10.4.14, 6.2.57, 9.5.25, 7.6.51, 8.7.40, 11.1.1
- Packagist typo3/cms: affected >= 10.0.0, < 10.4.14; >= 11.0.0, < 11.1.1; >= 9.0.0, < 9.5.25; fixed in 10.4.14, 9.5.25, 11.1.1

## Suggested inspection (read-only)
- Packagist typo3/cms-core: check the installed version with your package manager.
- Packagist typo3/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on typo3/cms-core, typo3/cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4jhw-2p6j-5wmp (GitHub-reviewed advisory GHSA-4jhw-2p6j-5wmp lists affected ranges: Packagist typo3/cms-core >=6.2.0 =7.0.0 =8.0.0 =10.0.0 =11.0.0 =9.0.0 =10.0.0 =11.0.0 =9.0.0 <9.5.25)

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