CVE-2020-9819 — Apple iOS, iPadOS, and watchOS Memory Corruption Vulnerability

A memory consumption issue was addressed with improved memory handling. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5, watchOS 5.3.7. Processing a maliciously crafted mail message may lead to heap corruption.

01What is this vulnerability?

A memory consumption issue was addressed with improved memory handling. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5, watchOS 5.3.7. Processing a maliciously crafted mail message may lead to heap corruption.

02Affected products

Vendor	Product	Versions
Apple	iOS	unspecified
Apple	iOS	1 — unspecified
Apple	watchOS	unspecified
Apple	watchOS	1 — unspecified

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2021-11-03. Ransomware use: Unknown.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

Open in Sigma generator →

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2020-06-09T16:12:28.000Z
• Last modified: 2025-12-20T04:55:57.815Z
• Added to CISA KEV: 2021-11-03
• BOD 22-01 due: 2022-05-03

09References

• support.apple.com — https://support.apple.com/HT211168
• support.apple.com — https://support.apple.com/HT211175
• support.apple.com — https://support.apple.com/HT211169
• support.apple.com — https://support.apple.com/HT211176