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Vulnerabilities

Vulnerability · CVE-2020-9818

Apple iOS, iPadOS, and watchOS Out-of-Bounds Write Vulnerability

Published Apr 22, 2020 · catalog updated Jun 16, 2026 · Apple iOS, iPadOS, and watchOS

Patch now

CVE-2020-9818 is in the CISA known-exploited catalog, due May 3, 2022. Confirm Apple iOS, iPadOS, and watchOS against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
High8.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
2.29%
Remediation
Remediation guidance
Affected products
cpe apple/ipados · cpe apple/iphone os · cpe apple/watchos · vendor Apple iOS, iPadOS, and watchOS

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe apple/ipadosversion unspecified
  • cpe apple/iphone osversion unspecified
  • cpe apple/watchosversion unspecified
  • vendor Apple iOS, iPadOS, and watchOSversion unspecified

How to fix CVE-2020-9818

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2020-9818 is in the CISA known-exploited catalog, due May 3, 2022. Confirm Apple iOS, iPadOS, and watchOS against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply updates per vendor instructions.

What should an analyst verify?

CWE-787: Out-of-bounds Write. EPSS 2.29%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 9, 2020 · Catalog

    Detected

    An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. May 3, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

Sources

  • CISA KEVConfirmed exploitationCVE-2020-9818

    Apple iOS, iPadOS, and watchOS Mail contains an out-of-bounds write vulnerability which may allow memory modification or application termination when processing a maliciously crafted mail message.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2020-9818

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2020-9818

    30-day exploitation probability 2.3%

    first.org
  • NIST NVDVulnerability recordCVE-2020-9818

    An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2020-9818

    Apple iOS, iPadOS, and watchOS Mail contains an out-of-bounds write vulnerability which may allow memory modification or application termination when processing a maliciously crafted mail message.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.