CVE-2025-43327 Overview
CVE-2025-43327 is an address bar spoofing vulnerability affecting Apple Safari and macOS Tahoe. The flaw allows a malicious website to manipulate the browser's address bar display, misleading users about the true origin of the content they are viewing. Apple addressed the issue by adding additional logic in Safari 26 and macOS Tahoe 26. The vulnerability is classified under [CWE-451] (User Interface (UI) Misrepresentation of Critical Information) and carries a network attack vector with no privileges or user interaction required beyond visiting a crafted page.
Critical Impact
Attackers can present a trusted URL in the Safari address bar while serving attacker-controlled content, enabling convincing phishing and credential theft campaigns.
Affected Products
- Apple Safari (versions prior to Safari 26)
- Apple macOS Tahoe (versions prior to macOS Tahoe 26)
- WebKit-based browsing components on affected macOS releases
Discovery Timeline
- 2025-09-15 - CVE-2025-43327 published to the National Vulnerability Database (NVD)
- 2025-09-15 - Apple releases Safari 26 and macOS Tahoe 26 with the fix
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-43327
Vulnerability Analysis
The vulnerability resides in Safari's handling of URL rendering within the address bar. A malicious website can trigger a state where the address bar displays a URL that does not correspond to the origin actually serving the page content. This mismatch breaks a foundational browser security assumption: that the URL shown to the user reflects the origin of the loaded document. Apple's advisory states the fix required "adding additional logic," indicating that specific navigation or rendering edge cases were not properly validated before updating the visible URL. Because the flaw is a display-level issue, it does not directly grant code execution, but it undermines the trust indicators users rely on to identify legitimate sites.
Root Cause
The root cause is improper synchronization between the navigation state and the address bar UI component. When certain navigation sequences occur, Safari updates the displayed URL before or independently of committing the underlying document origin. This maps to [CWE-451], where security-relevant information presented to the user does not accurately reflect the underlying application state.
Attack Vector
Exploitation requires a victim to visit an attacker-controlled webpage. The attacker crafts navigation sequences, redirects, or JavaScript-driven interactions that cause Safari to display a spoofed URL, such as a well-known banking or corporate domain, while rendering attacker content. The attacker can then present a convincing login form or fake security prompt to harvest credentials, session tokens, or multi-factor authentication codes.
No verified proof-of-concept code has been published. Refer to the Apple Support Document 125113 and Apple Support Document 125110 for vendor technical details.
Detection Methods for CVE-2025-43327
Indicators of Compromise
- Safari browser versions earlier than 26 running on macOS endpoints in the enterprise fleet
- macOS builds earlier than Tahoe 26 present in inventory and MDM reporting
- Outbound connections from Safari to newly registered or low-reputation domains immediately followed by credential submission events
- User reports of unexpected login prompts or session re-authentication requests while browsing familiar sites
Detection Strategies
- Query endpoint management and inventory tooling for Safari and macOS versions to identify unpatched hosts
- Correlate web proxy or DNS logs for visits to suspicious domains followed by POST requests carrying authentication parameters
- Monitor identity provider logs for anomalous authentication attempts originating from macOS endpoints shortly after browsing sessions
- Deploy phishing-aware email and URL filtering to reduce the likelihood of users reaching malicious pages that leverage the spoof
Monitoring Recommendations
- Track Safari and macOS patch compliance through MDM dashboards and generate alerts for hosts that remain on vulnerable versions
- Enable browser telemetry ingestion into the SIEM to correlate navigation events with subsequent credential activity
- Alert on impossible-travel or new-device sign-ins that follow browsing sessions on non-compliant endpoints
How to Mitigate CVE-2025-43327
Immediate Actions Required
- Update all macOS endpoints to macOS Tahoe 26 and Safari 26 through MDM-managed software update policies
- Prioritize patching for users with access to sensitive systems such as finance, executive, and privileged administrative roles
- Communicate to users that they should verify TLS certificate details, not just the address bar, when submitting credentials
- Review recent authentication logs for anomalies that predate the patch rollout
Patch Information
Apple resolved CVE-2025-43327 in Safari 26 and macOS Tahoe 26 by adding additional logic to the address bar update path. Patch guidance is documented in the Apple Support advisory 125113 and the companion Apple Support advisory 125110. Additional third-party discussion is available in the Full Disclosure list archive.
Workarounds
- Where immediate patching is not possible, restrict Safari usage for sensitive workflows and direct users to an alternate, updated browser
- Enforce phishing-resistant authentication such as FIDO2 or platform passkeys, which bind credentials to the true origin and defeat address bar spoofing
- Enable strict URL filtering and reputation-based blocking at the network perimeter to reduce exposure to spoofing landing pages
- Deliver targeted user awareness reminders about verifying site identity through certificate inspection rather than the address bar alone
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
