CVE-2021-45485: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-45485 is a vulnerability discovered in the IPv6 implementation of the Linux kernel before version 5.13.3. The vulnerability exists in net/ipv6/output_core.c where there is an information leak due to certain use of a hash table which, although large, doesn't properly consider that IPv6-based attackers can typically choose among many IPv6 source addresses (NVD, CVE).

The vulnerability stems from the IPv6 implementation's use of a hash table for packet ID generation. The original code used a siphash-based approach that didn't adequately account for attackers' ability to choose from multiple IPv6 source addresses. The issue was fixed by replacing the hash table mechanism with a direct use of prandom_u32() for ID generation, as IPv6 only uses packet IDs with fragments and has a minimum MTU of 1280, making it less susceptible to forced fragment generation (Kernel Commit). The vulnerability has a CVSS v3.1 Base Score of 7.5 (HIGH) with vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (NVD).

Successful exploitation of this vulnerability could lead to disclosure of sensitive information. The information leak could potentially weaken some protocols like DNS if packet IDs can be predicted with sufficient probability (NetApp Advisory).

The vulnerability was fixed in Linux kernel version 5.13.3. The fix involves replacing the hash table-based ID generation with direct use of prandom_u32(). Organizations should upgrade to Linux kernel version 5.13.3 or later to address this vulnerability (Kernel Commit).