CVE-2021-1883

Name: CVE-2021-1883
Creator: NVD / NIST
Published: 2021-09-08T15:15:12.513+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 1.97%

Last modified Jun 17, 2026

CVE-2021-1883 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. 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. EPSS estimates a 1.97% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS Probability

1.97%

77.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Apple	Ipados	< 14.5
Apple	Iphone Os	< 14.5
Apple	Mac Os X	>= 10.14, <= 10.14.5
Apple	Mac Os X	>= 10.15, <= 10.15.5
Apple	Mac Os X	10.14.6
Apple	Mac Os X	10.15.6
Apple	Mac Os X	10.15.7
Apple	Macos	>= 11.0, < 11.3
Apple	Tvos	< 14.5
Apple	Watchos	< 7.4

References

https://support.apple.com/en-us/HT212317Vendor Advisory
https://support.apple.com/en-us/HT212323Vendor Advisory
https://support.apple.com/en-us/HT212324Vendor Advisory
https://support.apple.com/en-us/HT212325Vendor Advisory
https://support.apple.com/en-us/HT212530Vendor Advisory
https://support.apple.com/en-us/HT212531Vendor Advisory
https://support.apple.com/en-us/HT212317Vendor Advisory
https://support.apple.com/en-us/HT212323Vendor Advisory
https://support.apple.com/en-us/HT212324Vendor Advisory
https://support.apple.com/en-us/HT212325Vendor Advisory
https://support.apple.com/en-us/HT212530Vendor Advisory
https://support.apple.com/en-us/HT212531Vendor Advisory

Timeline

Published: Sep 8, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-1883?

How severe is CVE-2021-1883?

CVE-2021-1883 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 1.97% probability of exploitation in the next 30 days.

How do I fix CVE-2021-1883?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-1883?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST