CVE-2026-53218
netfilter: nft_exthdr: fix register tracking for F_PRESENT flag
Description
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.
INFO
Published Date :
June 25, 2026, 8:39 a.m.
Last Modified :
June 25, 2026, 8:39 a.m.
Remotely Exploit :
No
Source :
Linux
Affected Products
The following products are affected by CVE-2026-53218
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update the Linux kernel to incorporate the fix.
- Validate user-controlled length against F_PRESENT flag.
- Ensure registers are properly initialized before use.
- Bail out if userspace requests too much data.
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CVE-2026-53218 vulnerability anywhere in the article.