When a challenge ACK is to be sent tcp_respond() constructs and sends the challenge ACK and consumes the mbuf that is passed in. When no challenge ACK should be sent the function returns and leaks the mbuf. If an attacker is either on path with an established TCP connection, or can themselves establish a TCP connection, to an affected FreeBSD machine, they can easily craft and send packets which meet the challenge ACK criteria and cause the FreeBSD host to leak an mbuf for each crafted packet in excess of the configured rate limit settings i.e. with default settings, crafted packets in excess of the first 5 sent within a 1s period will leak an mbuf. Technically, off-path attackers can also exploit this problem by guessing the IP addresses, TCP port numbers and in some cases the sequence numbers of established connections and spoofing packets towards a FreeBSD machine, but this is harder to do effectively.
This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.5, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 1 product from freebsd organizations running these solutions should prioritize assessment and patching.
Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2026-03-26T07:16:20.387
2026-04-30T18:55:51.180
Analyzed
CVSSv3.1: 7.5 (HIGH)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.3 | Yes |
| Operating System | freebsd | freebsd | 14.4 | Yes |
| Operating System | freebsd | freebsd | 14.4 | Yes |
| Operating System | freebsd | freebsd | 15.0 | Yes |
| Operating System | freebsd | freebsd | 15.0 | Yes |
| Operating System | freebsd | freebsd | 15.0 | Yes |
| Operating System | freebsd | freebsd | 15.0 | Yes |
| Operating System | freebsd | freebsd | 15.0 | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For freebsd's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.