# CVE-2021-26957: RUSTSEC-2021-0019 - Multiple soundness issues

Source: https://junglewise.ai/threats/cve-2021-26955-unchecked-return-value-in-xcb  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-02-04  
License: CC BY 4.0 with a link back

CVE-2021-26957 · Severity: low · CVSS 3.1 · Published 2021-02-04

Multiple soundness issues

Technologies: [xcb (crates.io)](https://junglewise.ai/threats/technologies/xcb). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io).

## Quick answers

**Is CVE-2021-26957 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-26957 being exploited in the wild.

**How severe is CVE-2021-26957?** Low severity, with a CVSS score of 3.1, published 4 February 2021.

**Which products and versions are affected?** xcb (crates.io) SEMVER:introduced=0,fixed=1.0.0, SEMVER:introduced=0.0.0-0,fixed=1.0.0.

**Is there a fix for CVE-2021-26957?** Yes. xcb (crates.io): upgrade to 1.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2021-26957?** Check whether you run xcb (crates.io) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- xcb (crates.io): upgrade to 1.0.0 or later

  ```sh
  cargo update -p xcb
  ```


## Affected products

- xcb (crates.io) SEMVER:introduced=0,fixed=1.0.0, SEMVER:introduced=0.0.0-0,fixed=1.0.0

## Identifiers

- CVE-2021-26957
- CVE-2021-26956
- CVE-2021-26958
- CVE-2021-26955
- GHSA-2xpg-3hx4-fm9r
- GHSA-3288-cwgw-ch86
- GHSA-3cj3-jrrp-9rxf
- GHSA-mp6r-fgw2-rxfx
- RUSTSEC-2021-0019

## Related threats

- [Rust XCB `xcb::Connection::connect_to_fd*` functions violate I/O safety](https://junglewise.ai/threats/rust-xcb-xcb-connection-connect-to-fd-functions-violate-i-o-safety-1e29deda)
- [RUSTSEC-2025-0051 - `xcb::Connection::connect_to_fd*` functions violate I/O safety](https://junglewise.ai/threats/rustsec-2025-0051-xcb-connection-connect-to-fd-functions-violate-i-o-4629362d)
- [RUSTSEC-2020-0097 - Soundness issue with base::Error](https://junglewise.ai/threats/cve-2020-36205-memory-handling-issues-in-xcb)