FreeBSD SO_REUSEPORT_LB wrong session

Summaryinfo

A vulnerability classified as critical has been found in FreeBSD. This issue affects some unknown processing of the component SO_REUSEPORT_LB Handler. The manipulation leads to wrong session. This vulnerability is documented as CVE-2025-24934. The attack can be initiated remotely. There is not any exploit available. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in FreeBSD (version now known) and classified as problematic. This issue affects some unknown processing of the component SO_REUSEPORT_LB Handler. The manipulation with an unknown input leads to a wrong session vulnerability. Using CWE to declare the problem leads to CWE-488. The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session. Impacted is integrity. The summary by CVE is:

Software which sets SO_REUSEPORT_LB on a socket and then connects it to a host will not directly observe any problems. However, due to its membership in a load-balancing group, that socket will receive packets originating from any host. This breaks the contract of the connect(2) and implied connect via sendto(2), and may leave the application vulnerable to spoofing attacks. The kernel failed to check the connection state of sockets when adding them to load-balancing groups. Furthermore, when looking up the destination socket for an incoming packet, the kernel will match a socket belonging to a load-balancing group even if it is connected, in violation of the contract that connected sockets are only supposed to receive packets originating from the connected host.

The weakness was released by Omer Ben Simhon. It is possible to read the advisory at security.freebsd.org. The identification of this vulnerability is CVE-2025-24934 since 01/29/2025. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/23/2025).

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-35613). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Operating System

Name

• FreeBSD

License

• open-source

Website

• Product: https://www.freebsd.org/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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