What is CVE-2023-41991?

CVE-2023-41991 is a medium-severity vulnerability in Apple iOS And Ipados, classified under Improper Certificate Validation. CVSS score: 5.5/10. Published 2023-09-21.

How severe is CVE-2023-41991?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Is CVE-2023-41991 known to be exploited?

Yes. CVE-2023-41991 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-09-25), indicating it is being actively exploited. 22 public proof-of-concept repositories are indexed.

Vulnerability in Apple iOS And Ipados

CVE-2023-41991

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.

Vulnerability class: Improper Certificate Validation

Published 2023-09-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.134 (96.4th percentile), scored 2026-10-18.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 96th percentile — 96.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.045 · newest: 0.134 · change: +0.088

Affected products

Apple iOS And Ipados — versions unspecified
Apple Ipados — versions 17.0
Apple Iphone OS — versions 17.0
Apple macOS — versions unspecified

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2023-09-25. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2023-10-16.

Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Public proof-of-concept exploits

References

support.apple.com/en-us/HT213927 (Vendor Advisory)
support.apple.com/en-us/HT213931 (Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2023-41991?: CVE-2023-41991 is a medium-severity vulnerability in Apple iOS And Ipados, classified under Improper Certificate Validation. CVSS score: 5.5/10. Published 2023-09-21.
How severe is CVE-2023-41991?: Medium severity. CVSS v3 base score is 5.5 out of 10.
Is CVE-2023-41991 known to be exploited?: Yes. CVE-2023-41991 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-09-25), indicating it is being actively exploited. 22 public proof-of-concept repositories are indexed.