CVE-2021-1782
Apple Multiple Products Race Condition Vulnerability
Description
CVE-2021-1782 is a high-severity race condition vulnerability affecting Apple iOS, iPadOS, macOS, watchOS, and tvOS. The flaw resides in the kernel's locking mechanisms, where an improper locking issue allows a malicious application to elevate privileges. CISA has added CVE-2021-1782 to its Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation. With an EPSS score of 7.9% (91.9th percentile), this Apple kernel race condition vulnerability poses a significant privilege escalation risk across the entire Apple device ecosystem.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorCWEs
Affected Products
| Vendor | Product | Version |
|---|---|---|
| apple | ipados | < 14.4 |
| apple | iphone os | < 14.4 |
| apple | mac os x | >= 10.14, < 10.14.6; >= 10.15, < 10.15.7; 10.14.6; 10.15.7 |
| apple | macos | >= 11.0, < 11.2 |
| apple | tvos | < 14.4 |
| apple | watchos | < 7.3 |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://support.apple.com/en-us/HT212146(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT212147(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT212148(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT212149(Release Notes, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1782(US Government Resource)
Weakness Type
CWE-667: Improper Locking
Improper locking occurs when software incorrectly uses synchronization primitives to control access to shared resources. In CVE-2021-1782, the Apple kernel fails to properly manage locking around shared resources, creating a race condition that a malicious application can exploit to elevate its privileges to kernel level.
Learn more: CWE-667 — Improper Locking
Impact Analysis
CVE-2021-1782 carries a CVSS 3.1 score of 7.0 (HIGH), reflecting a significant threat despite the higher attack complexity. The vulnerability requires local access and low-level privileges, but no user interaction is needed, meaning a malicious application can silently exploit the flaw without user awareness. Although the attack complexity is high due to the race condition timing requirements, successful exploitation results in high impact to confidentiality, integrity, and availability as the attacker gains elevated kernel privileges. The EPSS score of 7.9% (91.9th percentile) indicates a substantial probability of active exploitation. Apple has acknowledged that this issue may have been actively exploited, making it a critical priority for all affected platforms.
Exploit Maturity
CVE-2021-1782 is confirmed as actively exploited through its inclusion in the CISA Known Exploited Vulnerabilities catalog. Apple has acknowledged reports of active exploitation in the wild. The EPSS score of 7.9% (91.9th percentile) indicates a high probability of exploitation activity. While no public exploit code was identified in the available references, the confirmed active exploitation status demonstrates that sophisticated threat actors have successfully weaponized this race condition. Federal agencies were required to remediate by 2021-11-17 per CISA's binding operational directive.
Remediation
- Apply vendor patches immediately as mandated by CISA KEV: Apply updates per vendor instructions. Update to iOS 14.4/iPadOS 14.4, macOS Big Sur 11.2, watchOS 7.3, or tvOS 14.4.
- For macOS systems running older versions, apply Security Update 2021-001 Catalina or Security Update 2021-001 Mojave as appropriate for your operating system version.
- Restrict the installation of untrusted applications through MDM policies, app store restrictions, and code signing enforcement to reduce the risk of malicious applications exploiting this privilege escalation vulnerability.
- Monitor endpoints for signs of privilege escalation, including processes running with unexpected elevated permissions, unusual kernel extension loading, and suspicious system modification activity.
- Enable and verify that System Integrity Protection (SIP) is active on macOS systems, and ensure that kernel integrity protections are not disabled on any managed device.
Technical Details
CVE-2021-1782 is a race condition vulnerability in the Apple kernel caused by improper locking of shared resources. The flaw involves incorrect synchronization primitives that fail to properly control concurrent access to kernel data structures. According to the CVSS vector (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H), the vulnerability requires local access with low privileges and high attack complexity but no user interaction. The race condition arises when multiple threads access shared kernel resources without adequate locking, allowing a carefully timed malicious application to corrupt kernel state and escalate its privileges. Apple addressed this issue with improved locking mechanisms across macOS Big Sur 11.2, iOS 14.4, iPadOS 14.4, watchOS 7.3, and tvOS 14.4.
Frequently Asked Questions
Is CVE-2021-1782 being actively exploited?
Yes. CVE-2021-1782 is listed in the CISA Known Exploited Vulnerabilities catalog, and Apple has acknowledged reports of active exploitation. The EPSS score of 7.9% (91.9th percentile) further confirms a high exploitation probability.
What products are affected by CVE-2021-1782?
CVE-2021-1782 affects a broad range of Apple products: iPhone OS (< 14.4), iPadOS (< 14.4), macOS (>= 11.0, < 11.2), Mac OS X (>= 10.14, < 10.14.6; >= 10.15, < 10.15.7; 10.14.6; 10.15.7), tvOS (< 14.4), and watchOS (< 7.3).
How do I fix CVE-2021-1782?
Apply updates per vendor instructions. Update to iOS 14.4, iPadOS 14.4, macOS Big Sur 11.2, watchOS 7.3, or tvOS 14.4. For older macOS versions, apply the appropriate Security Update 2021-001. Restrict installation of untrusted applications via MDM policies.
How severe is CVE-2021-1782?
CVE-2021-1782 has a CVSS 3.1 score of 7.0 (HIGH). While attack complexity is high due to the race condition timing requirements, successful exploitation grants kernel-level privilege escalation, and its confirmed active exploitation status makes it a critical remediation priority.
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