CVE-2023-41991: Apple Multiple Products Improper Certificate Validation Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 25 Sep 2023, 4 days after the CVE record was published.

How likely is exploitation in the next 30 days?

13.4%

EPSS score, percentile 96.4 of all scored records

How severe?

5.5 Medium

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 16 Oct 2023. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

• before 16.7
• before 13.6

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 16 October 2023.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://support.apple.com/en-us/HT213926
• https://support.apple.com/en-us/HT213927
• https://support.apple.com/en-us/HT213928
• https://support.apple.com/en-us/HT213929
• https://support.apple.com/en-us/HT213931
• https://nvd.nist.gov/vuln/detail/CVE-2023-41991

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Apple iOS, iPadOS, macOS, and watchOS contain an improper certificate validation vulnerability that can allow a malicious app to bypass signature validation.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2023-41991 to its Known Exploited Vulnerabilities (KEV) catalog on 25 Sep 2023.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 16 Oct 2023.
• The CVE record was published on 21 Sep 2023, 4 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 5.5 (Medium), taken from CISA's enrichment of the record.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 13.4% (percentile 96.4), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

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: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-295: Improper Certificate Validation

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• support.apple.com
• support.apple.com

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• CVE-2026-65400: Apple macOS Improper Authentication Vulnerability (added 18 Aug 2026)
• CVE-2025-31277: Apple Multiple Products Buffer Overflow Vulnerability (added 20 Mar 2026)
• CVE-2025-43510: Apple Multiple Products Improper Locking Vulnerability (added 20 Mar 2026)
• CVE-2025-43520: Apple Multiple Products Classic Buffer Overflow Vulnerability (added 20 Mar 2026)
• CVE-2021-30952: Apple Multiple Products Integer Overflow or Wraparound Vulnerability (added 5 Mar 2026)