What’s Vulnerable › Vulnerabilities

CVE-2021-1883

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-09-08 · updated 2026-06-17
• Weakness: CWE-787

Description

This issue was addressed with improved checks. This issue is fixed in Security Update 2021-004 Mojave, iOS 14.5 and iPadOS 14.5, watchOS 7.4, Security Update 2021-003 Catalina, tvOS 14.5, macOS Big Sur 11.3. Processing maliciously crafted server messages may lead to heap corruption.

Affected products

• Apple iPadOS: before 14.5 — fixed in 14.5
• Apple Iphone Os: before 14.5 — fixed in 14.5
• macOS: from 10.14 through 10.14.5; from 10.15 through 10.15.5; 10.14.6, 10.14.6-security_update_2019-001, 10.14.6-security_update_2019-002, 10.14.6-security_update_2019-004, 10.14.6-security_update_2019-005, 10.14.6-security_update_2019-006 (+23)
• Apple macOS: from 11.0 before 11.3 — fixed in 11.3
• Apple tvOS: before 14.5 — fixed in 14.5
• Apple watchOS: before 7.4 — fixed in 7.4

How to fix

Upgrade to a fixed version: Apple iPadOS 14.5; Apple Iphone Os 14.5; Apple macOS 11.3; Apple tvOS 14.5; Apple watchOS 7.4. Check the vendor advisory for mitigations.

References

• https://support.apple.com/en-us/HT212317
• https://support.apple.com/en-us/HT212323
• https://support.apple.com/en-us/HT212324
• https://support.apple.com/en-us/HT212325
• https://support.apple.com/en-us/HT212530
• https://support.apple.com/en-us/HT212531
• https://support.apple.com/en-us/HT212317
• https://support.apple.com/en-us/HT212323
• https://support.apple.com/en-us/HT212324
• https://support.apple.com/en-us/HT212325
• https://support.apple.com/en-us/HT212530
• https://support.apple.com/en-us/HT212531

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