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Vulnerabilities

Vulnerability · CVE-2021-1879

Apple iOS, iPadOS, and watchOS WebKit Cross-Site Scripting (XSS) Vulnerability

Published Mar 26, 2021 · catalog updated Jun 16, 2026 · Apple iOS, iPadOS, and watchOS

Patch now

CVE-2021-1879 is in the CISA known-exploited catalog, due Nov 17, 2021. 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
Medium6.1
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
7.08%
Remediation
Remediation guidance
Affected products
cpe apple/ipados · cpe apple/iphone os · cpe apple/watchos · vendor Apple iOS, iPadOS, and watchOS

Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

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-2021-1879

What to do

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

Should you patch?

CVE-2021-1879 is in the CISA known-exploited catalog, due Nov 17, 2021. 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-79: Cross-site Scripting (XSS). EPSS 7.08%. 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. Apr 2, 2021 · Catalog

    Detected

    Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

Sources

  • CISA KEVConfirmed exploitationCVE-2021-1879

    Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2021-1879

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-1879

    30-day exploitation probability 7.1%

    first.org
  • NIST NVDVulnerability recordCVE-2021-1879

    This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue m

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2021-1879

    Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari

    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.