# CVE-2026-98590: bpf: Fix bpf_sock context code generation

> A flaw in Linux kernel BPF socket context code generation allows local attackers to bypass verifier checks, potentially leading to privilege escalation or code execution.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109410, BELL-CVE-2026-98590, DEBIAN-CVE-2026-98590, GHSA-6ffg-3w9m-mjpv, UBUNTU-CVE-2026-98590

## What is CVE-2026-98590?

CVE-2026-98590 is a memory corruption vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix bpf_sock context code generation

Currently, the ctx access code reads the rx_queue_mapping
field with either a 4-byte or 2-byte load. The rest of the bits
in the register are marked known zero by the verifier. However,
the emitted ctx access code places in the register on certain
the special value (-1) using BPF_MOV_IMM64, which gets sign-extended
to turn on all the bits in the register. By shifting this value right,
the program ends up with a value at runtime above what the verifier
assumes is possible.

Fix this by ensuring the read value is as wide as the assumed size.
Use MOV32 instructions instead of MOV64 instructions to keep
the upper bits zero as assumed by the verifier. Also properly report
the size of the destination variable (the bpf_sock field, 4 bytes) instead
of the source (the socket field, 2 bytes).

## Which versions are affected by CVE-2026-98590?


## How do I fix CVE-2026-98590?

Apply the vendor's patch.

## Is CVE-2026-98590 being exploited?

There is no known exploitation of CVE-2026-98590 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98590 and fix it if it is affected.

What it is: CVE-2026-98590 is a memory corruption vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98590 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98590/ (Markdown: https://insights.sbomify.com/CVE-2026-98590/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98590
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98590
- OSV: https://osv.dev/vulnerability/CVE-2026-98590

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98590/
Summaries are generated and may contain mistakes; the official description above is the record.