CVE-2026-70279: Microsoft Exchange Server 2016 Cumulative Update 23 · Cross-site Scripting

Attack Vector: Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

Attack Complexity: Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

Privileges Required: None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.

User Interaction: Required

Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.

Scope: Changed

An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.

Confidentiality: High

There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.

Integrity: High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability: None

There is no impact to availability within the impacted component.

Exploit Code Maturity: Unproven

No exploit code is available, or an exploit is theoretical.

Remediation Level: Official Fix

A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.

Report Confidence: Confirmed

Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability.

Definitions: FIRST CVSS v3.1 specification.