---
id: CVE-2020-15254
aliases:
  - GHSA-v5m7-53cv-f3hx
  - CVE-2020-35904
  - GHSA-m8h8-v6jh-c762
  - RUSTSEC-2020-0052
title: crossbeam-channel Undefined Behavior before v0.4.4
summary: crossbeam-channel Undefined Behavior before v0.4.4
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
vendor: crossbeam-channel
product: crossbeam-channel
ecosystem: rust
affected:
  - 'crossbeam-channel >= 0.4.3, < 0.4.4'
patched:
  - crossbeam-channel 0.4.4
published: '2021-08-25'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-v5m7-53cv-f3hx'
references:
  - url: >-
      https://github.com/crossbeam-rs/crossbeam/security/advisories/GHSA-v5m7-53cv-f3hx
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2020-15254'
  - url: 'https://github.com/crossbeam-rs/crossbeam/issues/539'
  - url: 'https://github.com/RustSec/advisory-db/pull/425'
  - url: 'https://github.com/crossbeam-rs/crossbeam/pull/533'
  - url: 'https://github.com/crossbeam-rs/crossbeam'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2020-0052.html'
tags:
  - osv
  - rust
epss: 0.02701
epssPercentile: 0.85328
ingestedAt: '2026-07-09T18:56:37.329Z'
---

## Overview

### Impact

The affected version of this crate's the `bounded` channel incorrectly assumes that `Vec::from_iter` has allocated capacity that same as the number of iterator elements. `Vec::from_iter` does not actually guarantee that and may allocate extra memory. The destructor of the `bounded` channel reconstructs `Vec` from the raw pointer based on the incorrect assumes described above. This is unsound and causing deallocation with the incorrect capacity when `Vec::from_iter` has allocated different sizes with the number of iterator elements.

### Patches

This has been fixed in crossbeam-channel 0.4.4.

We recommend users to upgrade to 0.4.4.

### References

See https://github.com/crossbeam-rs/crossbeam/pull/533, https://github.com/crossbeam-rs/crossbeam/issues/539, and https://github.com/RustSec/advisory-db/pull/425 for more details.

### License

This advisory is in the public domain.

## Affected packages

- `crossbeam-channel >= 0.4.3, < 0.4.4`

## Remediation

Upgrade to a patched release:

- `crossbeam-channel 0.4.4`