The Linux kernel's netfilter nft_exthdr module had a flaw where nft_exthdr_init() passed a user-controlled length value to nft_parse_register_store(), marking that many bytes in the register bitmap as initialized. However, when the NFT_EXTHDR_F_PRESENT flag is set, only 1 or 4 bytes are actually written during evaluation, leaving registers beyond the first uninitialized and retaining stack data. This discrepancy could cause use of uninitialized memory. The fix involves bailing out if userspace requests more data than allowed when F_PRESENT is set, preventing the retention of uninitialized stack data.

The vulnerability does not impact confidentiality or integrity but can cause availability issues (denial of service) due to use of uninitialized stack data. There are no known exploits in the wild. The CVSS score is 5.5 (medium severity) with local attack vector, low complexity, low privileges required, no user interaction, unchanged scope, and no confidentiality or integrity impact.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official patch links are provided in the available data. Users should monitor vendor advisories for updates and apply official fixes once available. Until then, avoid exposing vulnerable kernel components to untrusted userspace inputs that could trigger this condition.