What’s Vulnerable › Vulnerabilities

CVE-2026-98631: xsk: Use a 32-bit compare in xsk_map_gen_lookup

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-18 · updated 2026-10-19

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.

Affected products

• Linux kernel: 5.5 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

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

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