# CVE-2026-74715: bpf: Fix netns reference imbalance in conntrack kfuncs

> A race condition in Linux kernel BPF conntrack kfuncs allows attackers to cause a kernel panic and denial of service via namespace reference imbalance.

- **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
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-97341, BELL-CVE-2026-74715, DEBIAN-CVE-2026-74715, GHSA-8qqv-vcf6-q7hx, UBUNTU-CVE-2026-74715

## What is CVE-2026-74715?

CVE-2026-74715 is a high-severity vulnerability in Linux, published on 22 Aug 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 netns reference imbalance in conntrack kfuncs

The opts argument of the BPF conntrack kfuncs can point to a shared
map value.  __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry() read
opts->netns_id separately when acquiring and releasing the network
namespace reference.

The reference imbalance can occur as follows:

  CPU 0                                  CPU 1
  read opts->netns_id (-1)
  skip get_net_ns_by_id()
                                         write opts->netns_id (id)
  read opts->netns_id (id)
  put_net(net) /* no matching get */

The reverse transition leaks the reference.  Repeating the unmatched put
can destroy a live namespace and crash later users.

The kernel reported:

  Oops: general protection fault, probably for non-canonical address
  KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef]
  RIP: 0010:bpf_prog_test_run_xdp+0x52c/0x1700
  Call Trace:
   __sys_bpf+0x1662/0x50c0
   __x64_sys_bpf+0x73/0xb0
   do_syscall_64+0xf9/0x540
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  Kernel panic - not syncing: Fatal exception

Snapshot every input field of opts with READ_ONCE() before validating or
using it.  The netns_id snapshot keeps the namespace get/put pair
balanced, while the other snapshots keep the remaining options from
changing partway through an invocation.  The individual reads can still
observe an inconsistent combination during a concurrent update, but each
selected field value remains stable for that invocation.

## Which versions are affected by CVE-2026-74715?


## How do I fix CVE-2026-74715?

Apply the vendor's patch.

## Is CVE-2026-74715 being exploited?

There is no known exploitation of CVE-2026-74715 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74715 and fix it if it is affected.

What it is: CVE-2026-74715 is a high-severity vulnerability in Linux, published on 22 Aug 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-2026-74715 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-2026-74715/ (Markdown: https://insights.sbomify.com/CVE-2026-74715/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74715
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74715
- OSV: https://osv.dev/vulnerability/CVE-2026-74715

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74715/
Summaries are generated and may contain mistakes; the official description above is the record.