CVE-2022-2588: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-2588 is a vulnerability discovered in the Linux kernel's cls_route filter implementation where an old filter would not be removed from the hashtable before being freed if its handle had a value of 0. The vulnerability was discovered by Zhenpeng Lin working with Trend Micro's Zero Day Initiative and was present since Linux v2.6.12-rc2 (Openwall, Kernel Patch).

The vulnerability exists in the route4change function where there is a mismatch between conditions for removing and freeing filters. When replacing a filter with handle value 0, the code fails to unlink the old filter from the list before freeing it, leading to a use-after-free condition. The bug requires CAPNET_ADMIN capabilities in any user or network namespace to exploit (Openwall). The vulnerability has been assigned a CVSS score of 8.8 (AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H) (ZDI Advisory).

The vulnerability can be exploited for Local Privilege Escalation, allowing attackers to cause a denial of service (system crash) or execute arbitrary code with root privileges. A local attacker could use this vulnerability to escalate privileges and execute code in the context of root (Ubuntu Security, ZDI Advisory).

Users who do not rely on clsroute can mitigate the vulnerability by adding 'install clsroute /bin/true' to their modprobe.conf or modprobe.d configs if it's built as a module. The vulnerability has been fixed in various Linux distributions through kernel updates. Ubuntu has released patches for multiple versions including 22.04 LTS, 20.04 LTS, 18.04 ESM, and 16.04 ESM (Openwall, Ubuntu Security).