Exploited CVEs / Apple / CVE-2023-41991

CVE-2023-41991

Apple Multiple Products Improper Certificate Validation Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2023-10-16 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Apple security releases, linked below.

Risk summary

MediumCISA KEV

5.5

CVSS base

4.5%

EPSS exploit probability

Medium

Severity

2023-09-25

Added to KEV

2023-10-16 (past due)

CISA due date

Actively exploited Apple Multiple Products vulnerability, Medium severity, CVSS 5.5. Added to the CISA KEV catalog 2023-09-25.

Senserva AI read on CVE-2023-41991 CISA required action Official fix for CVE-2023-41991 Admin questions

Senserva AI Opinion for CVE-2023-41991

A malicious app can bypass Apple's signature validation through this improper certificate validation flaw in iOS, iPadOS, macOS, and watchOS. Signature bypass is the enabler in spyware chains: it lets unsigned attacker code masquerade as trusted, which is why it was exploited in targeted attacks despite a modest Medium Severity rating (CVSS 5.5) and 5% EPSS. CISA added it to the KEV list in September 2023 alongside two companion Apple flaws.

Do this: Update all managed Apple devices, including watches, and verify MDM shows the fleet on patched OS builds.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2023-41991

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2023-41991, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2023-41991.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2023-41991: Apple Multiple Products Improper Certificate Validation Vulnerability
- Affected: Apple Multiple Products
- Severity: Medium, CVSS 5.5; EPSS 30-day exploitation probability 4.5%
- Added to CISA KEV: 2023-09-25; federal remediation due 2023-10-16
- Ransomware-linked: no
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch now

Exploited in the wild: confirmed by the CISA KEV catalog, not predicted.

The fix ships from the vendor: Apple security releases.

Do this now: Federal remediation deadline 2023-10-16; treat it as your outer bound. Patch now and verify deployment on every exposed device.

Updated August 14, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2023-41991

Published: 2023-09-25
Last revised: 2023-09-25
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

2023-09-25 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 5.5; EPSS first scored at 4.5%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2023-10-16 (past due).

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

Official fix for CVE-2023-41991

The authoritative fix and affected-version list are published by the vendor. Find the Multiple Products advisory on Apple security releases.

Apple security releases CISA KEV entry

Common questions about CVE-2023-41991

Is CVE-2023-41991 actively exploited?

Yes. CVE-2023-41991 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2023-09-25, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 4.5%.

What is the CISA deadline and required action for CVE-2023-41991?

CISA set the federal (BOD 22-01) remediation due date at 2023-10-16, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What fixes CVE-2023-41991?

The authoritative fix is in the vendor advisory: see Apple security releases for the patched Multiple Products versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2023-41991?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2023-41991's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).

Scope and sources

More exploited Apple CVEs: CVE-2025-31277 CVE-2025-43520 CVE-2025-43510 CVE-2021-30952 CVE-2023-43000 CVE-2023-41974 CVE-2026-20700 CVE-2025-43529
All Apple exploited CVEs on one page: Apple vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.