CVE-2026-98631
Published Oct 18, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: xsk: Use a 32-bit compare in xsk_map_gen_lookup xsk_map_gen_lookup() loads a u32 key and compares it with max_entries using BPF_JMP_IMM. BPF immediates are sign-extended to 64 bits, so a max_entries value of 0x80000000 or higher becomes a threshold larger than every zero-extended 32-bit key. An out-of-range index then skips the bounds check and the generated lookup reads past xsk_map[]. Compare with BPF_JMP32_IMM so the check stays in 32-bit unsigned range.
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References
Other References
https://git.kernel.org/stable/c/11d9be35c1f4233798e99be98bc474f83a254c6c
https://git.kernel.org/stable/c/123f90f394ca404ab8796a7c8072ff7fa5b65a9c
https://git.kernel.org/stable/c/227ec890559e922e235eb543646e3bf0bd8269b0
https://git.kernel.org/stable/c/36461e58f88a1b723f86693f437ac12e60ff4363
https://git.kernel.org/stable/c/3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24
https://git.kernel.org/stable/c/70504de0bb627848667207bec7ccfd647deb8814
https://git.kernel.org/stable/c/b5c0cff0c5331582ab01c4c423731453a8381acc
https://git.kernel.org/stable/c/c6d5c582d55a8f229d75e98d62eaa065b0deb18d
Frequently Asked Questions
What is CVE-2026-98631? +
In the Linux kernel, the following vulnerability has been resolved:
xsk: Use a 32-bit compare in xsk_map_gen_lookup
xsk_map_gen_lookup() loads a u32 key and compares it with max_entries
using BPF_JMP_IMM. BPF immediates are sign-extended to 64 bits, so a
max_entries value of 0x80000000 or higher becomes a threshold larger
than every zero-extended 32-bit key. An out-of-range index then skips
the bounds check and the generated lookup reads past xsk_map[].
Compare with BPF_JMP32_IMM so the check stays in 32-bit unsigned range.
How do I check if I'm vulnerable to CVE-2026-98631? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.