Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-06-25T00:00:00 kernel: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-824

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag nft_exthdr_init() passes user-controlled priv->len to nft_parse_register_store(), which marks that many bytes in the register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT is set, the eval paths write only 1 byte (nft_reg_store8) or 4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nft_regs. Bail out if userspace requests too much data when F_PRESENT is set.

A flaw was found in the Linux kernel's netfilter component. This vulnerability occurs in the `nft_exthdr` module when handling user-controlled data lengths with a specific flag, `NFT_EXTHDR_F_PRESENT`, enabled. An attacker could exploit this by providing a crafted input, leading to the exposure of uninitialized stack memory. This information disclosure could potentially reveal sensitive system data.

Red Hat Enterprise Linux 10 Affected kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Affected kernel Red Hat Enterprise Linux 8 Affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel Red Hat Enterprise Linux 9 Affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-53218 https://nvd.nist.gov/vuln/detail/CVE-2026-53218 https://lore.kernel.org/linux-cve-announce/2026062505-CVE-2026-53218-d36e@gregkh/T