# CVE-2026-90312: bpf: Check load-acquire src ptr type before the load


- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-90312, DEBIAN-CVE-2026-90312, GHSA-4gcp-c78x-x35m, UBUNTU-CVE-2026-90312

## What is CVE-2026-90312?

CVE-2026-90312 is a high-severity vulnerability in Linux, published on 17 Sep 2026. 

### Official description

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

bpf: Check load-acquire src ptr type before the load

check_atomic_load() calls check_load_mem() before atomic_ptr_type_ok().
For a load-acquire that fetches into its own source register (dst_reg ==
src_reg), check_load_mem() overwrites src_reg's type with the type of the
loaded value, so the subsequent atomic_ptr_type_ok() no longer sees the
source pointer and fails to reject the disallowed types (ctx, pkt,
flow_keys, sock).

Since bpf_convert_ctx_accesses() does not rewrite atomic loads, the raw
access to the underlying kernel object is left in place. The destination
type is taken from the ctx access itself, so a load-acquire of the sk
field of struct __sk_buff for example leaves the register typed as
PTR_TO_SOCK_COMMON_OR_NULL, which type_is_sk_pointer() does not match
either, while it actually holds unconverted struct sk_buff bytes. Once
the NULL check has passed this is a type confusion, not just a leak of
kernel data.

Validate src_reg with check_reg_arg() and check the source pointer type
with atomic_ptr_type_ok() before the load again, mirroring
check_atomic_rmw(). Out-of-range register numbers are already rejected
earlier by check_and_resolve_insns() (commit 503d21ef8eac ("bpf: Do
register range validation early")), and the only exemption there,
is_stack_arg_ldx(), requires BPF_LDX | BPF_MEM | BPF_DW and thus never
matches a BPF_ATOMIC insn. atomic_ptr_type_ok() can therefore not
dereference register state out of bounds, that is, the out-of-bounds
read addressed by the Fixes commit below does not reappear (as proven
also via selftest).

## Which versions are affected by CVE-2026-90312?


## How do I fix CVE-2026-90312?

Upgrade to a fixed version.

## Is CVE-2026-90312 being exploited?

There is no known exploitation of CVE-2026-90312 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90312 and fix it if it is affected.

What it is: CVE-2026-90312 is a high-severity vulnerability in Linux, published on 17 Sep 2026. 
Exploitation: There is no known exploitation of CVE-2026-90312 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-2026-90312/ (Markdown: https://insights.sbomify.com/CVE-2026-90312/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90312
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90312
- OSV: https://osv.dev/vulnerability/CVE-2026-90312

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90312/
Summaries are generated and may contain mistakes; the official description above is the record.