HTTP Host Header Injection

Exploitation

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

CVSS

4.8 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

EPSS

• CVE-2021-41114: 1.22% estimated exploitation activity in the next 30 days; percentile 68.74 (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.

Meta CVSS: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:F/RL:O/RC:C (3.5) Problem It has been discovered that TYPO3 CMS is susceptible to host spoofing due to improper validation of the HTTP Host header. TYPO3 uses the HTTP Host header, for example, to generate absolute URLs during the frontend rendering process. Since the host header itself is provided by the client, it can be forged to any value, even in a name-based virtual hosts environment. This vulnerability is the same as described in TYPO3-CORE-SA-2014-001 (CVE-2014-3941). A regression, introduced during TYPO3 v11 development, led to this situation. The already existing setting $GLOBALS['TYPO3CONFVARS']['SYS']['trustedHostsPattern'] (used as an effective mitigation strategy in previous TYPO3 versions) was not evaluated anymore, and reintroduced the vulnerability. Solution Update your instance to TYPO3 version 11.5.0 which addresses the problem described. Credits Thanks to TYPO3 framework merger Benjamin Franzke who reported…

Published by the source

5 Oct 2021, 20:23 UTC

Last modified by the source

5 Feb 2024, 11:18 UTC

Source last checked

26 Oct 2026, 14:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-m2jh-fxw4-gphm

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2021-41114

Advisory: HTTP Host Header Injection
IDs: CVE-2021-41114, GHSA-m2jh-fxw4-gphm
Record: https://patchnext.com/advisories/cve-2021-41114 (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 4.8)
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 11.5.0; typo3/cms 11.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist typo3/cms-core: affected >= 11.0.0, < 11.5.0; fixed in 11.5.0
- Packagist typo3/cms: affected >= 11.0.0, < 11.5.0; fixed in 11.5.0

## 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-m2jh-fxw4-gphm (GitHub-reviewed advisory GHSA-m2jh-fxw4-gphm lists affected ranges: Packagist typo3/cms-core >=11.0.0 =11.0.0 <11.5.0)

Commands are suggestions: review each one before running it.