---
id: "CVE-2023-42917"
kind: "vulnerability"
aliases: ["CVE-2023-42917"]
title: "A memory corruption vulnerability was addressed with improved locking"
severity: "critical"
cvss: 8.8
epss: null
exploited: true
status: "open"
category: "vendor"
products: [{"name": "Apple Multiple Products", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "apple safari", "fixed": ["17.1.2"], "affected": "< 17.1.2", "ecosystem": "vendor"}, {"name": "apple ipados", "fixed": ["15.8.1"], "affected": "< 15.8.1", "ecosystem": "vendor"}, {"name": "apple ipados", "fixed": ["16.7.3"], "affected": ">= 16.0, < 16.7.3", "ecosystem": "vendor"}, {"name": "apple ipados", "fixed": ["17.1.2"], "affected": ">= 17.0, < 17.1.2", "ecosystem": "vendor"}, {"name": "apple iphone os", "fixed": ["15.8.1"], "affected": "< 15.8.1", "ecosystem": "vendor"}, {"name": "apple iphone os", "fixed": ["16.7.3"], "affected": ">= 16.0, < 16.7.3", "ecosystem": "vendor"}, {"name": "apple iphone os", "fixed": ["17.1.2"], "affected": ">= 17.0, < 17.1.2", "ecosystem": "vendor"}, {"name": "apple macos", "fixed": ["14.1.2"], "affected": ">= 14.0, < 14.1.2", "ecosystem": "vendor"}, {"name": "debian linux", "fixed": [], "affected": "= 11.0", "ecosystem": "vendor"}, {"name": "debian linux", "fixed": [], "affected": "= 12.0", "ecosystem": "vendor"}, {"name": "fedoraproject fedora", "fixed": [], "affected": "= 38", "ecosystem": "vendor"}, {"name": "fedoraproject fedora", "fixed": [], "affected": "= 39", "ecosystem": "vendor"}, {"name": "webkitgtk webkitgtk\\+", "fixed": ["2.42.3"], "affected": "< 2.42.3", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "ios", "ipados", "macos", "safari", "vendor", "webkit"]
not_affected_if: ["fully-patched-devices"]
published_at: "2023-11-30T23:15:07+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-2023-42917", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-42917", "first_seen_at": "2026-10-23T22:29:04+00:00"}]
---

# A memory corruption vulnerability was addressed with improved locking

A memory corruption bug in Apple's WebKit engine, used by iOS, iPadOS, macOS and Safari, lets crafted web content run code. It is listed as actively 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 safari affected < 17.1.2 fixed 17.1.2
- vendor:apple ipados affected < 15.8.1 fixed 15.8.1
- vendor:apple ipados affected >= 16.0, < 16.7.3 fixed 16.7.3
- vendor:apple ipados affected >= 17.0, < 17.1.2 fixed 17.1.2
- vendor:apple iphone os affected < 15.8.1 fixed 15.8.1
- vendor:apple iphone os affected >= 16.0, < 16.7.3 fixed 16.7.3
- vendor:apple iphone os affected >= 17.0, < 17.1.2 fixed 17.1.2
- vendor:apple macos affected >= 14.0, < 14.1.2 fixed 14.1.2
- vendor:debian linux affected = 11.0 fixed ?
- vendor:debian linux affected = 12.0 fixed ?
- vendor:fedoraproject fedora affected = 38 fixed ?
- vendor:fedoraproject fedora affected = 39 fixed ?
- vendor:webkitgtk webkitgtk\+ affected < 2.42.3 fixed 2.42.3

## How to check

Check the device OS version under Settings > General > About (iOS/iPadOS) or Apple menu > About This Mac (macOS) and compare it to the patched release named by Apple.

## Fix

Update iOS, iPadOS, macOS and Safari to the patched versions Apple published for this CVE; CISA requires vendor remediation or discontinued use.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2023-42917
- 2026-10-23T22:29:04+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2023-42917

## From the sources

Apple iOS, iPadOS, macOS, and Safari WebKit contain a memory corruption vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

CISA required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

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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_