CVE-2026-27287: Adobe InCopy RCE Vulnerability

CVE-2026-27287 Overview

CVE-2026-27287 is an out-of-bounds read vulnerability affecting Adobe InCopy versions 20.5.2, 21.2 and earlier. The vulnerability occurs when parsing a crafted file, which could result in a read past the end of an allocated memory structure. An attacker could leverage this vulnerability to execute code in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Critical Impact

Successful exploitation allows arbitrary code execution with the privileges of the current user, potentially leading to full system compromise on affected Windows and macOS systems.

Affected Products

• Adobe InCopy versions 20.5.2 and earlier
• Adobe InCopy versions 21.2 and earlier
• Affected platforms: Microsoft Windows and Apple macOS

Discovery Timeline

• 2026-04-14 - CVE-2026-27287 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2026-27287

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-Bounds Read), a memory corruption issue that occurs when Adobe InCopy improperly handles the parsing of specially crafted files. During the file parsing process, the application fails to properly validate buffer boundaries, allowing read operations to access memory beyond the allocated structure. While out-of-bounds read vulnerabilities typically result in information disclosure, this particular flaw can be leveraged to achieve code execution by manipulating application control flow.

The attack requires local access and user interaction—specifically, the victim must be tricked into opening a malicious file. This could be delivered via phishing emails, malicious websites, or compromised document repositories. Once the victim opens the crafted file in Adobe InCopy, the attacker gains code execution capabilities within the context of the user's session.

Root Cause

The root cause stems from insufficient bounds checking during file parsing operations in Adobe InCopy. When the application processes certain file structures, it fails to validate that memory read operations remain within the bounds of allocated buffers. This allows an attacker to craft a file that triggers reads beyond the allocated memory region, potentially exposing sensitive data or enabling further exploitation to achieve code execution.

Attack Vector

The attack vector is local, requiring user interaction. An attacker must craft a malicious file and convince the target user to open it with Adobe InCopy. Common delivery mechanisms include:

• Phishing emails with malicious InCopy document attachments
• Compromised file-sharing platforms hosting weaponized documents
• Social engineering tactics to trick users into downloading and opening malicious files
• Watering hole attacks targeting creative professionals who commonly use Adobe InCopy

Once the malicious file is opened, the out-of-bounds read condition is triggered during the parsing phase, potentially allowing the attacker to execute arbitrary code with the victim's privileges.

Detection Methods for CVE-2026-27287

Indicators of Compromise

• Unexpected crash reports or error logs from Adobe InCopy related to memory access violations
• Presence of suspicious or unexpected InCopy document files in download folders or email attachments
• Unusual child processes spawned by the InCopy application
• Memory access anomalies detected by endpoint protection tools when InCopy processes documents

Detection Strategies

• Deploy endpoint detection rules to monitor Adobe InCopy for abnormal memory access patterns
• Implement file inspection capabilities to analyze InCopy documents before user access
• Configure application whitelisting to alert on unexpected executables spawned by InCopy processes
• Use behavioral analysis to detect post-exploitation activities following InCopy file opens

Monitoring Recommendations

• Monitor Adobe InCopy application logs for parsing errors or crash events
• Track file system activity for newly created InCopy documents from external sources
• Implement email gateway scanning for InCopy document attachments
• Enable Windows Event logging for application crashes and memory violations related to InCopy processes

How to Mitigate CVE-2026-27287

Immediate Actions Required

• Update Adobe InCopy to the latest patched version as specified in APSB26-33
• Restrict opening of InCopy documents from untrusted sources
• Implement application sandboxing where possible to limit the impact of successful exploitation
• Educate users about the risks of opening documents from unknown or untrusted sources

Patch Information

Adobe has released security updates to address this vulnerability. Organizations should apply the patches detailed in Adobe Security Advisory APSB26-33. The advisory provides specific version information and download links for the patched releases that remediate CVE-2026-27287.

Workarounds

• Avoid opening InCopy documents from untrusted or unknown sources until patches can be applied
• Implement network segmentation to limit the potential impact of successful exploitation
• Use virtual environments or sandboxed systems when handling documents from external parties
• Deploy strict email filtering to quarantine suspicious InCopy document attachments
• Consider temporarily restricting InCopy usage to essential workflows until the update is deployed