CyberSecBulletin
CVE-2023-41991Exploited in the wildNVD status: Analyzed

Apple Multiple Products Improper Certificate Validation

Published Updated By the CyberSecBulletin desk

CVE-2023-41991 is a medium-severity improper certificate validation vulnerability in iOS and iPadOS from Apple, with a CVSS 3.1 base score of 5.5 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 16.7 as the first without the flaw, so updating iOS and iPadOS to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on September 25, 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 iOS and iPadOS to 16.7 or a later version.
  2. Update macOS to 13.6 or a later version.
  3. Update iPadOS to 16.7 or a later version.
  4. CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
  5. Read the advisory on support.apple.com for workarounds and exact fixed builds.
  6. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
AppleiOS and iPadOSbefore 16.716.7
ApplemacOSbefore 13.613.6
AppleiPadOSbefore 16.7; 17.016.7
AppleIphone OSbefore 16.7; 17.016.7

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
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

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

Scoring systemScoreSeverityScored by
CVSS 3.15.5MediumNVD
CVSS 3.15.5MediumCISA (ADP)

Official description

A certificate validation issue was addressed. This issue is fixed in macOS Ventura 13.6, iOS 16.7 and iPadOS 16.7. A malicious app may be able to bypass signature validation. Apple is aware of a report that this issue may have been actively exploited against versions of iOS before iOS 16.7.

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

The underlying weakness: Improper Certificate Validation

The product does not validate, or incorrectly validates, a certificate.

How developers prevent this class of flaw

  • Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
  • If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.

More Improper Certificate Validation vulnerabilities (CWE-295)

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: partial).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in iOS and iPadOS

All iOS and iPadOS vulnerabilities

Recent Improper Certificate Validation vulnerabilities

Spotted an error? Tell us.