CVE-2025-21259 is a medium-severity vulnerability affecting Microsoft Outlook, specifically on Android devices. This vulnerability allows attackers to exploit the spoofing feature of Outlook, which may lead to unauthorized information being presented to users. The vulnerability has a CVSS score of 5.3, indicating a medium level of risk. Although the vulnerability does not directly compromise confidentiality or availability, its low attack complexity and lack of required privileges make it a concern for organizations relying on Outlook for communication.
The vulnerability was published on February 11, 2025, and has been analyzed by Microsoft. It impacts all versions of Outlook for Android prior to 4.2501.1. Given the nature of the vulnerability, organizations should prioritize addressing it in their patch cycles to reduce the risk of exploitation.
Risk to organizations includes potential reputational damage and loss of trust if users are misled by spoofed communications. Hence, organizations should take immediate action to patch affected systems and educate users about potential phishing attempts that may exploit this vulnerability.
Currently, there are no public exploits or proofs of concept available, and it is not listed as actively exploited in the Known Exploited Vulnerabilities (KEV) catalog. However, given the nature of spoofing vulnerabilities, organizations should remain vigilant.
Vulnerability Details
The official description of CVE-2025-21259 states that it is a Microsoft Outlook spoofing vulnerability. The vulnerability is classified under CWE-451, indicating a weakness related to 'User Interface Spoofing'. The CVSS score of 5.3 suggests that while the vulnerability is significant, it is not critical. The attack vector is network-based, and the attack complexity is low, meaning that it could be exploited easily by an attacker with no privileges required.
Organizations using Microsoft Outlook should ensure they are running versions later than 4.2501.1 to mitigate this vulnerability. The vulnerability was disclosed on February 11, 2025, and has been classified as analyzed by Microsoft.
Technical Analysis
The root cause of CVE-2025-21259 lies in the manner Microsoft Outlook processes certain data, allowing for spoofing. The attack vector is network-based, meaning an attacker could exploit this vulnerability remotely without physical access to the device. The attack complexity is categorized as low, indicating that minimal skill is required to exploit the vulnerability.
No user interaction is required, which raises the risk level as users may be unaware of the spoofing taking place. The vulnerability has a low impact on integrity, meaning while data may be misrepresented, it is not entirely compromised. There is no impact on confidentiality and availability.
Risk & Impact Analysis
The deployment of this vulnerability in real-world scenarios poses a risk as it can lead to miscommunication and potentially harmful actions based on misleading information. Organizations relying on Microsoft Outlook for their communications should be particularly cautious, as the blast radius could extend to all users of the application.
The urgency for addressing CVE-2025-21259 is marked as medium, given its CVSS score of 5.3 and the potential for exploitation. Although it is not currently listed in the KEV catalog, organizations should take proactive steps to patch their systems and prevent any possible exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Microsoft Outlook versions prior to 4.2501.1 on Android are affected by this vulnerability. Organizations should ensure that they have upgraded to this version or later to mitigate risks associated with CVE-2025-21259.
Mitigation & Remediation
Organizations should prioritize patching Microsoft Outlook on affected Android devices. The recommended version to upgrade to is 4.2501.1 or later. If a patch is unavailable, organizations should consider implementing additional network controls to limit exposure to potential spoofing attacks. Regular user training on recognizing phishing attempts and other social engineering tactics is also advisable.
Detection Guidance
Organizations should monitor logs for unusual email patterns or spoofed communications originating from Microsoft Outlook. Behavioral anomalies such as unexpected changes in user behavior or messaging patterns should be investigated. Additionally, network signatures indicating potential exploitation attempts should be established.
AppSecure Threat Intelligence Insight
CVE-2025-21259 highlights the ongoing risk of spoofing vulnerabilities in widely used applications like Microsoft Outlook. Organizations should take this as a reminder to continually assess their security posture and ensure that they have robust security measures in place. Implementing a comprehensive
penetration testing program can help identify similar vulnerabilities before they can be exploited.
Additionally, continuous monitoring and updates to security training programs for employees can significantly reduce the risk of exploitation from such vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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