CyberSecBulletin
CVE-2019-8526Exploited in the wildNVD status: Analyzed

Apple macOS Use-After-Free

Published Updated By the CyberSecBulletin desk

CVE-2019-8526 is a high-severity use after free vulnerability in macOS from Apple, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version macOS Mojave 10.14.4 as the first without the flaw, so updating macOS to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on April 17, 2023, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update macOS to macOS Mojave 10.14.4 or a later version.
  2. Update Mac OS X to 10.14.4 or a later version.
  3. CISA's required action: Apply updates per vendor instructions.
  4. Read the advisory on support.apple.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
ApplemacOSbefore macOS Mojave 10.14.4macOS Mojave 10.14.4
AppleMac OS Xbefore 10.14.410.14.4

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighNVD
CVSS 3.17.8HighCISA (ADP)
CVSS 2.07.2HighNVD

Official description

A use after free issue was addressed with improved memory management. This issue is fixed in macOS Mojave 10.14.4. An application may be able to gain elevated privileges.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Advisories

Third-party and government advisories

Other vulnerabilities in macOS

All macOS vulnerabilities

Recent Use After Free vulnerabilities

Spotted an error? Tell us.