CVE-2025-21760: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-21760 affects the Linux kernel's ndisc (Neighbor Discovery) component. The vulnerability was discovered and disclosed on February 26, 2025, involving a potential Use-After-Free (UAF) condition in the ndiscsendskb() function. The issue occurs because this function can be called without proper RTNL or RCU protection held (NVD).

The vulnerability stems from insufficient RCU (Read-Copy-Update) protection in the ndiscsendskb() function within the Linux kernel's IPv6 neighbor discovery implementation. The function could be called without proper RTNL (Route Netlink) or RCU locks held, potentially leading to a Use-After-Free condition. The CVSS v3.1 base score is 7.8 (HIGH) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability could potentially lead to a Use-After-Free condition in the Linux kernel's networking stack, which could result in system crashes, memory corruption, or potential privilege escalation. The high CVSS score indicates significant potential impact on system confidentiality, integrity, and availability (NVD).

The vulnerability has been patched by extending RCU protection in ndiscsendskb(). The fix involves acquiring rcureadlock() earlier in the function execution to ensure proper protection when using devnetrcu(). The patch has been reviewed by David Ahern and Kuniyuki Iwashima, and committed by Jakub Kicinski (Kernel Commit).