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Fencer Vulns
critical 9.8

CVE-2020-3909 json

A buffer overflow was addressed with improved bounds checking.

published 2020-04-01 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-25174

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.0%
EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

A buffer overflow was addressed with improved bounds checking. This issue is fixed in iOS 13.4 and iPadOS 13.4, macOS Catalina 10.15.4, tvOS 13.4, watchOS 6.2, iTunes for Windows 12.10.5, iCloud for Windows 10.9.3, iCloud for Windows 7.18. Multiple issues in libxml2.

Patch / fix

  • Apple iOS iOS 13.4 and iPadOS 13.4
  • Apple macOS macOS Catalina 10.15.4
  • Apple tvOS tvOS 13.4
  • Apple watchOS watchOS 6.2
  • Apple iTunes for Windows iTunes for Windows 12.10.5
  • Apple iCloud for Windows iCloud for Windows 10.9.3
  • Apple iCloud for Windows (Legacy) iCloud for Windows 7.18

Exploit prediction

3.04% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Apple iOS
  • Apple macOS
  • Apple tvOS
  • Apple watchOS
  • Apple iTunes for Windows
  • Apple iCloud for Windows
  • Apple iCloud for Windows (Legacy)

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

References

Sources

Fencer Vulns 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.