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CRITICAL severity

CVE-2019-16699

CRITICAL

CVE-2019-16699 is a critical-severity (CVSS 9.8) Improper Input Validation vulnerability in sr_freecap_project sr freecap. O3 Security detects and blocks CVE-2019-16699 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.

The sr_freecap (aka freeCap CAPTCHA) extension 2.4.5 and below and 2.5.2 and below for TYPO3 fails to sanitize user input, which allows execution of arbitrary Extbase actions, resulting…

Published
Oct 16, 2019
Updated
Jun 17, 2026
Affected
1 product
Patched
See advisory
Exploits
None indexed
Exploitation data as of Jun 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Description

The sr_freecap (aka freeCap CAPTCHA) extension 2.4.5 and below and 2.5.2 and below for TYPO3 fails to sanitize user input, which allows execution of arbitrary Extbase actions, resulting in Remote Code Execution.

Affected Products

1 product · 2 configurations
Application
sr freecapsr_freecap_project
≥ 2.5.0 && ≤ 2.5.2
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every sr_freecap_project sr freecap deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Remediation status

    No patch has shipped for CVE-2019-16699 yet — track the sr_freecap_project sr freecap advisory for a fixed release and apply the workarounds below in the meantime.

  3. Mitigate without a patch

    Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

  4. How O3 protects you

    O3 detects and blocks CVE-2019-16699 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2019-16699. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

The sr_freecap (aka freeCap CAPTCHA) extension 2.4.5 and below and 2.5.2 and below for TYPO3 fails to sanitize user input, which allows execution of arbitrary Extbase actions, resulting in Remote Code Execution.
O3 Security · Runtime Protection

Is CVE-2019-16699 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2019-16699 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.