CVE-2026-77131 Overview
CVE-2026-77131 affects a TYPO3 extension that integrates with the SYSSY project. When OpenSSL is unavailable on the server, the extension falls back to transmitting TYPO3 system information in cleartext instead of encrypting the payload. The flaw maps to [CWE-319: Cleartext Transmission of Sensitive Information]. Exploitation requires an attacker to already control the SYSSY project's API key, limiting practical attack surface. A network attacker positioned between the TYPO3 server and the SYSSY endpoint could still observe unencrypted system metadata in transit.
Critical Impact
System information about TYPO3 installations leaks in cleartext over the network when OpenSSL is not present, exposing configuration and environment data to passive network observers.
Affected Products
- TYPO3 SYSSY extension (see TYPO3 Security Advisory SA-2026-015)
- TYPO3 installations running the extension on servers without OpenSSL available
- Environments transmitting system telemetry to the SYSSY project
Discovery Timeline
- 2026-08-25 - CVE-2026-77131 published to NVD
- 2026-08-26 - Last updated in NVD database
Technical Details for CVE-2026-77131
Vulnerability Analysis
The TYPO3 SYSSY extension periodically sends system information to the SYSSY project's remote API. The extension is designed to encrypt this telemetry before transmission. When the PHP OpenSSL module is not available on the server, the extension does not fail closed. Instead, it transmits the same payload in cleartext over the network.
The exposed data includes TYPO3 system information used by the SYSSY project for inventory and monitoring. Any attacker with visibility into the network path between the TYPO3 server and the SYSSY endpoint can read the payload. The advisory notes that active exploitation additionally requires prior control of the project's API key.
Root Cause
The extension lacks a strict encryption requirement. Instead of aborting transmission when OpenSSL is missing, the code path degrades to a plaintext channel. This design decision violates the principle of failing securely and is the direct source of the [CWE-319] cleartext transmission weakness.
Attack Vector
The attack vector is network-based. A passive on-path adversary can capture the cleartext HTTP payload during outbound telemetry transmission. To correlate or misuse the data at the SYSSY endpoint, the attacker must also hold the project's API key, as stated in the vendor advisory. No authentication or user interaction is required for passive interception.
No public proof-of-concept code is available. The vulnerability is described in prose in the TYPO3 Security Advisory SA-2026-015.
Detection Methods for CVE-2026-77131
Indicators of Compromise
- Outbound HTTP requests from TYPO3 servers to SYSSY project endpoints that are not wrapped in TLS or that contain unencrypted JSON telemetry payloads
- PHP environments where openssl is not present in the loaded extensions list on servers running the SYSSY extension
- Web server or proxy logs showing SYSSY telemetry transmissions with content types indicating plaintext payloads
Detection Strategies
- Inspect egress traffic from TYPO3 hosts and flag SYSSY telemetry that lacks encryption envelopes
- Audit PHP module inventory on TYPO3 servers to identify hosts missing the OpenSSL extension
- Correlate SYSSY extension version data against the fixed release listed in the vendor advisory
Monitoring Recommendations
- Monitor outbound connections from TYPO3 web servers for unexpected cleartext data flows
- Alert on PHP configuration drift where the OpenSSL module becomes unavailable on production hosts
- Track TYPO3 extension inventories and flag versions predating the security fix
How to Mitigate CVE-2026-77131
Immediate Actions Required
- Update the TYPO3 SYSSY extension to the fixed version referenced in TYPO3 Security Advisory SA-2026-015
- Verify that the PHP openssl extension is installed and enabled on all TYPO3 servers running the SYSSY extension
- Rotate the SYSSY project API key if there is any indication it was exposed
Patch Information
Refer to the TYPO3 Security Advisory SA-2026-015 for the fixed release versions and installation guidance. Apply the patched version through the TYPO3 Extension Manager or Composer.
Workarounds
- Install and enable the PHP OpenSSL module on affected servers to force the extension onto its encrypted transmission path
- Temporarily disable the SYSSY extension on hosts where OpenSSL cannot be enabled until the update is applied
- Restrict outbound network access from TYPO3 servers to trusted endpoints and route SYSSY traffic through a TLS-terminating egress proxy
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
