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Fencer Intel
medium 6.1

CVE-2021-1879 kev in the critical feed json

This issue was addressed by improved management of object lifetimes.

published 5y ago modified 4mo ago also EUVD-2021-7343

cvss
6.1
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03
epss
7.1%
EPSS 7.1% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

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..

Patch / fix

cisa required action Apply updates per vendor instructions.

  • Apple iOS and iPadOS 14.4
  • Apple iOS 12.5
  • Apple watchOS 7.3

Is CVE-2021-1879 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Timeline

  1. 0-day patched (Project Zero)
  2. Published
  3. Added to CISA KEV
  4. CISA patch deadline
  5. CISA SSVC: exploitation active

Known exploited

Added
5y ago
Patch by
2021-11-17 (4y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
Apple, iOS, iPadOS, and watchOS
CISA name
Apple iOS, iPadOS, and watchOS WebKit Cross-Site Scripting (XSS) Vulnerability

Zero-day

Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.

Patched
2021-03-26
Details
project zero root cause analysis

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

7.08% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • Apple iOS and iPadOS
  • Apple iOS
  • Apple watchOS

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.