CVE-2025-31257: Apple Safari DOS Vulnerability

CVE-2025-31257 Overview

CVE-2025-31257 is a memory handling vulnerability affecting Apple Safari and multiple Apple operating systems. Processing maliciously crafted web content can trigger an unexpected Safari crash, resulting in a denial-of-service condition for the browser process. Apple addressed the issue with improved memory handling across Safari 18.5, iOS 18.5, iPadOS 18.5, macOS Sequoia 15.5, tvOS 18.5, visionOS 2.5, and watchOS 11.5. The flaw is categorized under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and requires user interaction to trigger.

Critical Impact

Remote attackers can crash Safari by luring users to maliciously crafted web pages, disrupting browser availability across Apple's ecosystem.

Affected Products

• Apple Safari (prior to 18.5)
• Apple iOS and iPadOS (prior to 18.5)
• Apple macOS Sequoia (prior to 15.5), tvOS (prior to 18.5), visionOS (prior to 2.5), and watchOS (prior to 11.5)

Discovery Timeline

• 2025-05-12 - CVE-2025-31257 published to NVD
• 2026-05-12 - Last updated in NVD database

Technical Details for CVE-2025-31257

Vulnerability Analysis

The vulnerability resides in Safari's handling of web content rendering. When Safari processes specially crafted web content, a memory handling defect leads to an unexpected termination of the browser process. The issue is classified under [CWE-119], indicating an operation that reads or writes outside the bounds of an allocated memory buffer.

Exploitation requires a victim to visit a malicious or compromised web page. No privileges are required on the target system, and the attack is network-reachable through standard web traffic. While confidentiality and integrity are not directly impacted, the availability of the Safari process is affected, producing a browser crash.

The vulnerability spans Safari and the WebKit-based rendering stack shared across iOS, iPadOS, macOS, tvOS, visionOS, and watchOS, which is why Apple shipped coordinated updates across the entire product portfolio.

Root Cause

The root cause is improper memory handling within the Safari web content processing path. Apple's advisory states the fix introduces improved memory handling, indicating that the original implementation did not adequately validate buffer boundaries or memory state when parsing or processing crafted web content.

Attack Vector

The attack vector is network-based via web content. An attacker hosts or injects malicious content into a page accessed by a victim using a vulnerable Safari version. User interaction is required: the victim must navigate to the attacker-controlled content. Because no authentication is required and the scope changes during exploitation, the crash can affect rendering processes beyond the initial origin context.

No public proof-of-concept code or exploit was referenced in available advisories. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog at the time of writing.

Detection Methods for CVE-2025-31257

Indicators of Compromise

• Repeated unexpected Safari or WebKit process crashes on iOS, iPadOS, macOS, tvOS, visionOS, or watchOS devices.
• Crash reports referencing WebKit rendering components following navigation to specific URLs.
• Browser logs showing abnormal termination shortly after loading external web content.

Detection Strategies

• Monitor endpoint telemetry for repeated Safari or com.apple.WebKit process crashes across managed Apple fleets.
• Correlate crash events with recent web navigation history to identify suspicious URLs or domains delivering crafted content.
• Inventory Apple device OS versions and flag systems running pre-18.5, pre-15.5, or pre-2.5 builds as in scope.

Monitoring Recommendations

• Collect and centralize macOS and iOS crash diagnostics for analyst review.
• Track outbound DNS and HTTP/S traffic to newly registered or low-reputation domains following crash events.
• Maintain version compliance dashboards for all Apple endpoints to track patch adoption.

How to Mitigate CVE-2025-31257

Immediate Actions Required

• Update Safari to version 18.5 and upgrade all Apple operating systems to the patched releases listed by Apple.
• Prioritize patching of internet-facing user endpoints that browse arbitrary web content.
• Enforce mobile device management (MDM) policies that block enrollment or access from devices running unpatched OS versions.

Patch Information

Apple resolved the issue with improved memory handling in Safari 18.5, iOS 18.5, iPadOS 18.5, macOS Sequoia 15.5, tvOS 18.5, visionOS 2.5, and watchOS 11.5. Full advisory details are available from Apple in Security Update Advisory 122404, Advisory 122716, Advisory 122719, Advisory 122720, Advisory 122721, and Advisory 122722. Downstream impact is also tracked in the Debian LTS Announcement and Siemens Security Advisory SSA-032379.

Workarounds

• Avoid visiting untrusted or unfamiliar websites in Safari until patches are applied.
• Use enterprise web filtering to block known malicious or low-reputation domains.
• Where feasible, route browsing through a hardened, fully patched alternative browser until Safari is updated.