CVE-2026-77146 TYPO3 CVE debrief

Who should care

Defenders responsible for Typo3 installations, particularly those using version 8.x of the extension, should assess exposure and verify user account security. This includes reviewing user account configurations, password reset processes, and implementing compensating controls to prevent unauthorized account access. Security teams should also prioritize verifying exposure and assessing potential impacts on their organizations.

Why it matters

CVE-2026-77146 allows unauthenticated attackers to set new passwords and re-enable arbitrary existing frontend user accounts in Typo3 extension versions 8.x, requiring defenders to verify exposure and assess user account security.

• Verify exposure of Typo3 extension versions 8.x to prevent unauthorized account access
• Assess user account security and password reset processes to prevent exploitation
• Implement compensating controls to prevent unauthorized account access and data breaches

Technical summary

The Typo3 extension's invitation controller fails to stop processing after redirecting on invalid input, allowing an unauthenticated attacker to set a new password for and re-enable an arbitrary existing frontend user account. This vulnerability is only present in the 8.x versions of the extension. The issue arises from the controller not properly handling redirects for invalid input such as missing hashes, non-existent users, disabled users, or deleted users. Defenders should prioritize verifying exposure of Typo3 extension versions 8.x and assessing user account security.

Defensive priority

Defenders should prioritize verifying exposure of Typo3 extension versions 8.x and assessing user account security.

Recommended defensive actions

• Verify exposure of Typo3 extension versions 8.x
• Assess user account security and password reset processes
• Implement compensating controls to prevent unauthorized account access
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability in the Typo3 extension's invitation controller, allowing unauthenticated attackers to set new passwords and re-enable arbitrary existing frontend user accounts.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.