CVE-2026-21514 is a high-severity vulnerability affecting Microsoft Office Word, specifically related to the reliance on untrusted inputs in security decisions. This flaw permits unauthorized attackers to bypass security features locally, which poses significant risks to the integrity and confidentiality of the affected systems. With a CVSS score of 7.8, this vulnerability represents a serious threat to organizations using the impacted Microsoft products.
The vulnerability has been publicly disclosed and has been classified as critical in terms of exploitability. Organizations utilizing Microsoft Office Word and its related applications, such as 365 Apps and the Office Long Term Servicing Channel, should prioritize patching this vulnerability to prevent potential exploitation.
Risk to organizations includes unauthorized access to sensitive documents and local privilege escalation, which can lead to further compromises within the network. Organizations should address this vulnerability in their priority patch cycle, given its high severity and the potential impact on data security.
As of now, there is no public proof-of-concept (PoC) or known exploit available for this vulnerability. However, given the nature of the issue, attackers may leverage it to gain unauthorized access. Therefore, organizations should remain vigilant and ensure timely remediation.
Organizations should prioritize patching immediately.
Vulnerability Details
The vulnerability is due to a reliance on untrusted inputs when making security decisions in Microsoft Office Word. This flaw can allow an unauthorized attacker to bypass intended security features locally, leading to a potential compromise of sensitive information. The vulnerability has a CVSS version 3.1 score of 7.8, indicating that it is high severity.
The affected products include Microsoft 365 Apps and the Office Long Term Servicing Channel. This vulnerability was published on February 10, 2026, and is associated with CWE-807, which refers to reliance on untrusted inputs.
Technical Analysis
The root cause of this vulnerability lies in the way Microsoft Office Word processes untrusted inputs. Attackers can exploit this weakness by providing inputs that the application does not adequately validate, leading to security decisions that can be bypassed.
The attack vector for this vulnerability is local, meaning an attacker would need to have local access to the system. The attack complexity is low, and no privileges are required to exploit this vulnerability, but user interaction is needed. This means that an attacker would need the user to open a malicious document or file.
If exploited, the potential impacts on confidentiality, integrity, and availability are all high, which indicates that this vulnerability poses a severe risk to the systems and data it affects.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2026-21514 is significant. Given that Microsoft Office is widely used in organizations, the blast radius for potential exploitation could affect numerous systems and sensitive data repositories.
Organizations should be particularly concerned about the potential for unauthorized access to confidential documents and the subsequent risk of data breaches, which can lead to financial losses and reputational damage.
Given the high CVSS score and its inclusion in the Known Exploited Vulnerabilities catalog, organizations should address this vulnerability in their priority patch cycle to mitigate risks effectively.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
The affected versions for this vulnerability include Microsoft 365 Apps and the Office Long Term Servicing Channel for both x64 and x86 architectures. Specific versions include 2021 and 2024 releases. If version information is missing, organizations should assume that all versions prior to the vendor patch are affected.
Mitigation & Remediation
Organizations should ensure they apply the necessary patches or updates provided by Microsoft to remediate this vulnerability. Following the guidance provided in the vendor advisory is critical for effective mitigation.
In case patches are not available, organizations should consider implementing configuration hardening and network controls to minimize exposure. Continuous monitoring for any unusual activity related to Microsoft Office applications is also advisable.
For more comprehensive security measures, organizations can engage in penetration testing to identify and address potential weaknesses.
Detection Guidance
Organizations should monitor logs for any indicators of exploitation attempts, such as unexpected file access or execution of malicious macros in Microsoft Office documents. Behavioral anomalies in user activity may also indicate attempts to exploit this vulnerability.
Network signatures can be developed to detect unusual traffic patterns associated with malicious Office document interactions.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-21514 lies in its representation of the ongoing challenges organizations face regarding untrusted inputs in application security. This incident highlights the need for robust input validation mechanisms in software development.
Security teams should note the patterns of reliance on untrusted inputs and consider implementing security frameworks that prioritize stringent validation processes. This proactive approach can help mitigate similar vulnerabilities in the future.
For further insights into application security best practices, organizations may refer to the following resources: application security assessments and penetration testing methodologies to strengthen defenses and reduce the risk of future vulnerabilities.
Organizations should continue to monitor this vulnerability for any updates or additional guidance from Microsoft.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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