# CVE-2026-46314: drm/v3d: Reject empty multisync extension to prevent infinite loop

> A local attacker can cause a kernel infinite loop and CPU exhaustion by submitting a crafted empty multisync extension to the v3d driver.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 8 Jun 2026
- **Updated:** 19 Jun 2026
- **Also known as:** AZL-89639, BELL-CVE-2026-46314, DEBIAN-CVE-2026-46314, GHSA-24m2-rchh-h2mx, ROOT-OS-DEBIAN-12-CVE-2026-46314, ROOT-OS-DEBIAN-13-CVE-2026-46314, ROOT-OS-UBUNTU-2404-CVE-2026-46314, UBUNTU-CVE-2026-46314

## What is CVE-2026-46314?

CVE-2026-46314 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 Jun 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:

drm/v3d: Reject empty multisync extension to prevent infinite loop

v3d_get_extensions() walks a userspace-provided singly-linked list of
ioctl extensions without any bound on the chain length. A local user
can craft a self-referential extension (ext->next == &ext) with zero
in_sync_count and out_sync_count, which bypasses the existing duplicate-
extension guard:

    if (se->in_sync_count || se->out_sync_count)
            return -EINVAL;

The guard never fires because v3d_get_multisync_post_deps() returns
immediately when count is zero, leaving both fields at zero on every
iteration. The result is an infinite loop in kernel context, blocking
the calling thread and pegging a CPU core indefinitely.

Fix this by rejecting a multisync extension where both in_sync_count
and out_sync_count are zero in v3d_get_multisync_submit_deps(). An
empty multisync carries no synchronization information and serves no
useful purpose, so returning -EINVAL for such an extension is the
correct defense against this attack vector.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-46314?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46314?

Apply the vendor's patch.

## Is CVE-2026-46314 being exploited?

There is no known exploitation of CVE-2026-46314 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46314 and fix it if it is affected.

What it is: CVE-2026-46314 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 Jun 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-2026-46314 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46314/ (Markdown: https://insights.sbomify.com/CVE-2026-46314/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46314
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46314
- OSV: https://osv.dev/vulnerability/CVE-2026-46314

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46314/
Summaries are generated and may contain mistakes; the official description above is the record.