CVE-2021-1879

MEDIUM

6.1

CVSS Score

Published: April 2, 2021 at 06:07 PM UTC

Updated: June 17, 2026 at 03:32 AM UTC

3 products affected across 1 vendoriPhone OSiPadOSwatchOS

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Severity

MEDIUM6.1

Exploitation

CISA KEV

Exploit prediction

EPSS 7%

SSVC

Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score7.1%

EPSS (Exploit Prediction Scoring System) estimates a 7.1% chance this CVE is exploited in the wild within the next 30 days — higher than 94% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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.

Required Action

Apply updates per vendor instructions.

Ransomware Use

Unknown

Added to KEV

Nov 3, 2021

Remediation Due

Nov 17, 2021

1806 days overdue

Notes

https://nvd.nist.gov/vuln/detail/CVE-2021-1879

Description

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 may have been actively exploited..

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

iPadOS · Apple

95%

v < 14.4v < 14.4.2

Affected range stops below 14.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 14.4.2, so it looks safe — our inference, not a vendor statement

iPhone OS · Apple

95%

v < 12.5v < 12.5.213.0 ≤ v < 14.4.2

Affected range stops below 12.5, so it looks safe — our inference, not a vendor statement

Affected range stops below 12.5.2, so it looks safe — our inference, not a vendor statement

Affected range stops below 14.4.2, so it looks safe — our inference, not a vendor statement

watchOS · Apple

95%

v < 7.3v < 7.3.3

Affected range stops below 7.3, so it looks safe — our inference, not a vendor statement

Affected range stops below 7.3.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (4)

x_refsource_MISCRelease NotesVendor Advisory

Source: [email protected]

https://support.apple.com/en-us/HT212256

x_refsource_MISCRelease NotesVendor Advisory

Source: [email protected]

https://support.apple.com/en-us/HT212257

x_refsource_MISCRelease NotesVendor Advisory

Source: [email protected]

https://support.apple.com/en-us/HT212258

US Government Resource

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1879

SSVC — Action Prioritization

SSVCActiveNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.1MEDIUMCISA-ADP

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: REQUIRED
Scope: CHANGED
Confidentiality: LOW
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-79

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