CVE-2026-55145 in Outlook
Summary
by MITRE • 07/14/2026
Improper neutralization of special elements used in a command ('command injection') in Outlook Copilot allows an authorized attacker to perform tampering over a network.
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Analysis
by VulDB Data Team • 07/15/2026
Command injection vulnerabilities occur when user-supplied data is improperly incorporated into system commands without adequate sanitization or validation measures. This particular vulnerability in Outlook Copilot represents a critical security flaw that enables authenticated attackers to execute arbitrary commands on the underlying system through carefully crafted inputs. The weakness stems from insufficient input validation and output encoding mechanisms within the command execution pipeline, allowing malicious payloads to be interpreted as legitimate commands rather than data.
The technical implementation of this vulnerability involves the improper handling of user-controllable parameters within command construction processes. When Outlook Copilot processes user inputs for system operations, it fails to properly sanitize or escape special characters that have significance in command-line contexts such as semicolons, ampersands, pipes, and backticks. This allows attackers who have already established authentication credentials to manipulate the command execution flow by injecting malicious code sequences. The vulnerability operates at the application layer where user inputs are directly concatenated into system commands without proper contextual escaping or parameterization.
From an operational perspective, this command injection flaw significantly impacts the security posture of environments where Outlook Copilot is deployed. Authorized attackers can leverage this weakness to escalate privileges, access sensitive data, modify system configurations, or even establish persistent backdoors within the network infrastructure. The attack surface extends beyond individual user accounts to potentially compromise entire organizational systems, especially in environments where Copilot integrates with backend services or performs administrative functions. This vulnerability directly violates security principles outlined in the CWE-77 category for command injection flaws and aligns with ATT&CK technique T1059.001 for command and scripting interpreter.
The impact of this vulnerability extends to data confidentiality, integrity, and availability across affected systems. Attackers can execute commands that may result in unauthorized data exfiltration, system compromise, or disruption of services. The remediation approach requires comprehensive input validation mechanisms, proper command parameterization using secure APIs, and implementation of principle of least privilege controls. Organizations should implement strict input filtering, employ secure coding practices for command execution, and establish network segmentation to limit potential lateral movement. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in related components. The mitigation strategies must align with industry best practices for preventing command injection attacks and should include application-level controls such as input sanitization, output encoding, and secure API usage patterns that prevent the execution of unintended commands through user-supplied inputs.