# CVE-2026-46690: unbounded-spsc: Sender::send pointer-as-value transmute causes OOB read and fake-Arc drop under TX/RX race

> A race condition in the unbounded-spsc Rust library allows out-of-bounds reads and memory corruption via pointer transmutation, potentially leading to code execution or crashes.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/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:** No
- **Published:** 12 Jun 2026
- **Updated:** 12 Jun 2026
- **Also known as:** GHSA-6m57-8r3p-pqx6

## What is CVE-2026-46690?

CVE-2026-46690 is a medium-severity vulnerability in spearman unbounded-spsc, published on 12 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

unbounded_spsc is an "unbounded" extension of bounded_spsc_queue. In versions 0.2.0 and prior, sender::send pointer-as-value transmute causes OOB read and fake-Arc drop under TX/RX race. At time of publication, there are no publicly available patches.

Weakness: CWE-787 (Out-of-bounds Write), CWE-704 (Incorrect Type Conversion or Cast), CWE-415 (Double Free), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-46690?

2 open source packages ship an affected version, including unbounded-spsc. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `unbounded-spsc` | crates.io | All versions to 0.2.0 | None |
| `unbounded-spsc` | crates.io | All versions to 0.2.0 | None |

Products: Spearman Unbounded-Spsc.

## How do I fix CVE-2026-46690?

No fix has been published for CVE-2026-46690 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-46690 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46690 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46690 and fix it if it is affected.

What it is: CVE-2026-46690 is a medium-severity vulnerability in spearman unbounded-spsc, published on 12 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46690 exists.

Affected packages and fixed versions:
- unbounded-spsc (crates.io): affected all versions up to 0.2.0; no fix listed
- unbounded-spsc (crates.io): affected all versions up to 0.2.0; no fix listed

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-2026-46690/ (Markdown: https://insights.sbomify.com/CVE-2026-46690/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46690
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46690
- OSV: https://osv.dev/vulnerability/CVE-2026-46690

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46690/
Summaries are generated and may contain mistakes; the official description above is the record.