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Fencer Vulns
high 7.0

CVE-2021-30857 json

A race condition was addressed with improved locking.

published 2021-08-24 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-17774

cvss
7.0
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

A race condition was addressed with improved locking. This issue is fixed in Security Update 2021-005 Catalina, iOS 14.8 and iPadOS 14.8, tvOS 15, iOS 15 and iPadOS 15, watchOS 8, macOS Big Sur 11.6. A malicious application may be able to execute arbitrary code with kernel privileges.

Patch / fix

  • Apple macOS 8, 11.6, 14.8, 15, 2021

Exploit prediction

0.92% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 7.6 AV:N/AC:H/Au:N/C:C/I:C/A:C

Affected products

  • Apple macOS

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

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.