CVE-2025-31206: Apple Safari DoS Vulnerability

CVE-2025-31206 Overview

CVE-2025-31206 is a type confusion vulnerability in Apple's WebKit browser engine that affects Safari and multiple Apple operating systems. Processing maliciously crafted web content may trigger an unexpected Safari crash, resulting in a denial-of-service condition on the affected browser process. Apple addressed the issue with improved state handling across Safari 18.5, iOS 18.5, iPadOS 18.5, iPadOS 17.7.7, macOS Sequoia 15.5, tvOS 18.5, visionOS 2.5, and watchOS 11.5. The flaw is classified under CWE-843: Access of Resource Using Incompatible Type.

Critical Impact
A remote attacker who lures a user to a malicious website can crash the Safari browser process, disrupting the browsing session on any affected Apple device.

Affected Products

Apple Safari (prior to 18.5)
Apple iOS / iPadOS (prior to 18.5; iPadOS 17.7.7)
Apple macOS Sequoia (prior to 15.5), tvOS (prior to 18.5), visionOS (prior to 2.5), watchOS (prior to 11.5)

Discovery Timeline

2025-05-12 - CVE-2025-31206 published to the National Vulnerability Database (NVD)
2025-05-12 - Apple releases security updates 122404, 122405, 122716, 122719, 122720, 122721, and 122722
2025-06 - Debian LTS issues an advisory for downstream WebKit packages
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-31206

Vulnerability Analysis

The vulnerability is a type confusion flaw within WebKit, the browser engine that powers Safari and web content rendering across Apple platforms. Type confusion occurs when code allocates or accesses a resource assuming one object type while the underlying data represents a different type. When WebKit dereferences the mistyped object, it operates on memory with an incorrect layout, producing an unexpected process crash.

Exploitation is remote and network-based, but it requires user interaction. A victim must load attacker-controlled web content, typically by visiting a malicious URL or a compromised site. The confirmed impact is limited to availability, meaning the Safari renderer process terminates rather than leaking data or executing code. Similar WebKit type-confusion patterns have historically been chained with additional primitives to achieve memory corruption, so patching remains important even where the direct impact is a crash.

Root Cause

The root cause is improper state tracking of JavaScript or DOM objects inside WebKit, allowing an object to be interpreted as an incompatible type during processing. Apple's fix hardens state handling so that object types are validated before use, eliminating the confusion condition.

Attack Vector

The attack vector is a web page containing crafted JavaScript, HTML, or DOM manipulation logic that steers WebKit into the vulnerable code path. Delivery methods include direct navigation to a malicious domain, malvertising, embedded iframes on compromised sites, and phishing links delivered via email or messaging apps. No credentials are required, and no local access to the device is needed.

No verified public exploit code or proof-of-concept is currently available for CVE-2025-31206. Refer to the Apple security advisories and Full Disclosure archive posts from May 2025 for further technical context.

Detection Methods for CVE-2025-31206

Indicators of Compromise

Repeated or unexplained Safari or WebKit process crashes (com.apple.WebKit.WebContent) recorded in macOS or iOS crash logs.
Crash reports referencing type-checking assertions, JSC:: (JavaScriptCore) frames, or DOM object dispatch on affected Apple OS builds.
User-reported browser tab reloads or "A problem repeatedly occurred" prompts after visiting specific URLs.

Detection Strategies

Inventory Apple endpoints and correlate installed Safari and OS build numbers against the fixed versions listed in Apple advisories 122404, 122405, 122716, 122719, 122720, 122721, and 122722.
Ingest macOS unified logs and iOS CrashReporter diagnostics into a centralized log platform to identify anomalous WebKit terminations across the fleet.
Use web proxy and DNS telemetry to identify users visiting known malicious or newly registered domains hosting crafted web content.

Monitoring Recommendations

Alert on spikes in WebKit renderer crashes across managed devices, which may indicate probing or exploitation attempts.
Monitor Mobile Device Management (MDM) compliance reports to confirm iOS, iPadOS, macOS, tvOS, visionOS, and watchOS versions are at or above patched builds.
Track outbound connections from browser processes to suspicious domains observed in threat intelligence feeds covering WebKit exploitation activity.

How to Mitigate CVE-2025-31206

Immediate Actions Required

Update Safari to version 18.5 and update Apple operating systems to iOS 18.5, iPadOS 18.5, iPadOS 17.7.7, macOS Sequoia 15.5, tvOS 18.5, visionOS 2.5, or watchOS 11.5.
Enforce patch compliance for all managed Apple endpoints through MDM policies and block non-compliant devices from sensitive resources.
On Debian-based systems using downstream WebKitGTK, apply the fixes referenced in the Debian LTS announcement from June 2025.

Patch Information

Apple released fixes on 2025-05-12 across the following advisories: Safari 18.5 (122720), iOS 18.5 and iPadOS 18.5 (122716), iPadOS 17.7.7 (122719), macOS Sequoia 15.5 (122404), tvOS 18.5 (122721), visionOS 2.5 (122722), and watchOS 11.5 (122405). The patches introduce improved state handling in WebKit to eliminate the type confusion condition.

Workarounds

Restrict browsing to trusted sites and enforce URL filtering at the network edge until all endpoints are patched.
Configure content-blocking extensions or enterprise web filtering to block JavaScript execution on untrusted domains where feasible.
Advise users to avoid clicking links from untrusted email, messaging, or social media sources, since exploitation requires user interaction with attacker-controlled web content.

bash

# Verify Safari and macOS versions on managed endpoints
sw_vers -productVersion
defaults read /Applications/Safari.app/Contents/Info CFBundleShortVersionString

# Trigger MDM-managed software update on macOS
sudo softwareupdate --install --all --restart