How to fix CVE-2025-39950?

**CVE-2025-39950** is a unknown severity vulnerability affecting the affected product. **Description:** In the Linux kernel, the following vulnerability has been resolved: net/tcp: Fix a NULL pointer dereference when using TCP-AO with TCP_REPAIR A NULL pointer dereference can occur in tcp_ao_finish_connect() during a connect() system call on a socket with a TCP-AO key added and TCP_REPAIR enabled. The function is called with skb being NULL and attempts […] **Exploit Difficulty:** HARD ⏱️ Time to exploit: > 4 hours 🛠️ Required skills: Advanced security expertise 💰 Public exploits: Rare or not public **How to Fix:** 1. **Identify affected systems** - Check if you're running the affected product 2. **Immediate actions** - Update to the latest patched version - If patching is not immediately possible: restrict network exposure, apply least-privilege access 3. **Verification** - Test the fix in a staging environment first - Review logs for signs of exploitation - Monitor for IOCs (Indicators of Compromise) 4. **Long-term prevention** - Enable automatic security updates - Set up vulnerability monitoring - Review and harden security configurations

How severe is CVE-2025-39950?

This vulnerability has a CVSS score of (Unknown severity).

How difficult is it to exploit CVE-2025-39950?

Exploit difficulty: HARD. Estimated time to exploit: > 4 hours. Required skills: Advanced security expertise.

CVE-2025-39950

Published: 2025-10-04T08:15:48.253

In the Linux kernel, the following vulnerability has been resolved:

net/tcp: Fix a NULL pointer dereference when using TCP-AO with TCP_REPAIR

A NULL pointer dereference can occur in tcp_ao_finish_connect() during a
connect() system call on a socket with a TCP-AO key added and TCP_REPAIR
enabled.

The function is called with skb being NULL and attempts to dereference it
on tcp_hdr(skb)->seq without a prior skb validation.

Fix this by checking if skb is NULL before dereferencing it.

The commentary is taken from bpf_skops_established(), which is also called
in the same flow. Unlike the function being patched,
bpf_skops_established() validates the skb before dereferencing it.

int main(void){
struct sockaddr_in sockaddr;
struct tcp_ao_add tcp_ao;
int sk;
int one = 1;

memset(&sockaddr,’