CVE-2026-23010: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23010 is a use-after-free (UAF) vulnerability in the Linux kernel's IPv6 address configuration subsystem, specifically in the inet6_addr_del() function within net/ipv6/addrconf.c. A prior code change accidentally moved the ipv6_del_addr() call for mngtmpaddr before reading ifp->flags for temporary addresses, causing the inet6_ifaddr structure to be freed before its flags are accessed. The vulnerability was disclosed on January 25, 2026, and affects Linux kernel versions 6.1.120–6.1.161, 6.6.64–6.6.121, 6.11.11–6.11.x, 6.12.2–6.12.66, 6.13.1–6.18.6, and 6.19-rc1 through rc8. It carries a CVSS v3.1 base score of 7.8 (High) (Red Hat CVE, Red Hat Bugzilla).

The root cause is classified as CWE-416 (Use After Free). In inet6_addr_del(), a refactoring commit incorrectly reordered operations so that ipv6_del_addr() — which frees the inet6_ifaddr (ifp) structure — is called before the code reads ifp->flags to determine whether to handle temporary addresses. This results in a read of freed kernel heap memory. The vulnerability is triggered via the SIOCDELADDR ioctl on an IPv6 socket, reachable through the call chain: inet6_ioctl() → addrconf_del_ifaddr() → inet6_addr_del(). The bug was discovered by syzbot (Google's kernel fuzzer) and confirmed via KASAN reporting a slab-use-after-free at net/ipv6/addrconf.c:3117 (Red Hat Bugzilla).

Successful exploitation by a local low-privileged user can result in reading or writing arbitrary kernel memory, enabling privilege escalation to root, information disclosure of sensitive kernel data, or a kernel crash causing denial of service. The vulnerability's local attack vector limits its remote exploitability, but on multi-tenant systems (e.g., shared servers, container environments), it poses a meaningful risk of privilege escalation and lateral movement within the host. All three security dimensions — confidentiality, integrity, and availability — are rated High (Red Hat CVE).

1. Gain local access: Obtain a low-privileged shell on a system running a vulnerable Linux kernel version (6.1.120–6.1.161, 6.6.64–6.6.121, 6.12.2–6.12.66, or 6.13.1–6.18.6).
2. Open an IPv6 socket: Create a raw or UDP IPv6 socket using socket(AF_INET6, SOCK_DGRAM, 0) or similar.
3. Add a temporary IPv6 address: Use the SIOCSIFADDR or SIOCADDRT ioctl (or ip -6 addr add) to assign an IPv6 address with the IFA_F_MANAGETEMPADDR flag set, ensuring a mngtmpaddr entry is created.
4. Trigger the UAF: Issue the SIOCDELADDR ioctl on the socket targeting the address added in step 3. This calls inet6_addr_del(), which frees the inet6_ifaddr structure via ipv6_del_addr() before reading ifp->flags, triggering the use-after-free.
5. Exploit the memory corruption: Leverage the freed memory region (e.g., via heap spray or race condition techniques) to achieve arbitrary kernel read/write, potentially escalating privileges to root or crashing the kernel (Red Hat Bugzilla).

• Logs: Kernel logs (dmesg) showing BUG: KASAN: slab-use-after-free in inet6_addr_del or similar KASAN/KFENCE reports; kernel oops or panic messages referencing net/ipv6/addrconf.c:3117.
• Process: Unexpected processes issuing ioctl calls with SIOCDELADDR (0x8936) on IPv6 sockets, particularly from non-root users; unusual process behavior around IPv6 address management.
• Network: Repeated or anomalous IPv6 address addition and deletion operations on network interfaces, especially involving temporary addresses (IFA_F_MANAGETEMPADDR).
• System: Kernel crash dumps (vmcore) with stack traces referencing inet6_addr_del, addrconf_del_ifaddr, or inet6_ioctl in the call chain.

Patches are available in the stable Linux kernel repositories for the following fixed versions: 6.1.162+, 6.6.122+, 6.12.67+, and 6.18.7+. Red Hat addressed this in Red Hat Enterprise Linux 10 via errata RHSA-2026:4723. Ubuntu has issued security notices USN-8278-1, USN-8278-2, USN-8289-1, USN-8289-2, USN-8296-1, USN-8296-2, and USN-8393-1. SUSE addressed it via SUSE-2026:0962-1. As a short-term workaround, restrict local user access and limit the ability of unprivileged users to manipulate IPv6 addresses (e.g., via network namespace restrictions or removing CAP_NET_ADMIN from untrusted users). Prioritize kernel patching on multi-tenant or shared systems (Red Hat Errata, Red Hat Bugzilla, Ubuntu USN-8278-1).

The vulnerability was discovered by syzbot, Google's automated kernel fuzzing infrastructure, and reported to the Linux kernel security team. Red Hat triaged it as medium severity and addressed it in RHEL 10 via a dedicated errata. Multiple Linux distributions including Ubuntu, SUSE, Oracle Linux, AlmaLinux, and Rocky Linux have issued security advisories. No notable independent researcher commentary or significant social media discussion has been identified beyond standard vulnerability tracking and distribution advisory channels.