---
id: "CVE-2023-41991"
kind: "vulnerability"
aliases: ["CVE-2023-41991"]
title: "A certificate validation issue was addressed"
severity: "high"
cvss: 5.5
epss: null
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Apple Multiple Products", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "apple ipados", "fixed": ["16.7"], "affected": "< 16.7", "ecosystem": "vendor"}, {"name": "apple ipados", "fixed": [], "affected": "= 17.0", "ecosystem": "vendor"}, {"name": "apple iphone os", "fixed": ["16.7"], "affected": "< 16.7", "ecosystem": "vendor"}, {"name": "apple iphone os", "fixed": [], "affected": "= 17.0", "ecosystem": "vendor"}, {"name": "apple macos", "fixed": ["13.6"], "affected": ">= 13.0, < 13.6", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["apple-devices", "exploited", "infrastructure", "ios", "ipados", "macos", "watchos"]
not_affected_if: ["unknown"]
published_at: "2023-09-21T19:15:11+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T22:29:04+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2023-41991", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-41991", "first_seen_at": "2026-10-23T22:29:04+00:00"}]
---

# A certificate validation issue was addressed

Apple iOS, iPadOS, macOS and watchOS have an improper certificate validation flaw that lets a malicious app bypass signature validation. CISA lists it as known exploited in the wild.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Apple Multiple Products affected ? fixed ?
- vendor:apple ipados affected < 16.7 fixed 16.7
- vendor:apple ipados affected = 17.0 fixed ?
- vendor:apple iphone os affected < 16.7 fixed 16.7
- vendor:apple iphone os affected = 17.0 fixed ?
- vendor:apple macos affected >= 13.0, < 13.6 fixed 13.6

## Fix

Apply mitigations per vendor instructions or update to a fixed Apple OS release; the sources do not name the fixed versions.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2023-41991
- 2026-10-23T22:29:04+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2023-41991

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_