CVE-2026-26144
Published: 10 March 2026
Summary
CVE-2026-26144 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Microsoft 365 Apps. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 27.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.
Validates web inputs to reject script-related content that could produce XSS.
Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote network-accessible XSS (CWE-79) in Excel's web page generation directly maps to exploitation of a (web) application (T1190) and arbitrary JavaScript execution (T1059.007); the stated high-impact information disclosure enables data collection from the local system/browser context (T1005).
NVD Description
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
Deeper analysisAI
CVE-2026-26144, published on 2026-03-10, is a cross-site scripting (XSS) vulnerability classified under CWE-79 in Microsoft Office Excel. The issue arises from improper neutralization of input during web page generation, enabling an unauthorized attacker to disclose information over a network. It has a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high severity due to network accessibility, low attack complexity, and no requirements for privileges or user interaction.
An unauthorized attacker can exploit this vulnerability remotely without authentication or user involvement. Exploitation allows the attacker to achieve high-impact information disclosure over the network, potentially exposing sensitive data contained in or accessible via the affected Excel component, while leaving integrity and availability unaffected.
The Microsoft Security Response Center advisory provides details on mitigation and patches at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26144.
Details
- CWE(s)