CVE-2023-26369: Adobe Acrobat RCE Vulnerability Explained

CVE-2023-26369 Overview

CVE-2023-26369 is an out-of-bounds write vulnerability affecting Adobe Acrobat Reader that could result in arbitrary code execution in the context of the current user. This memory corruption flaw exists in multiple versions of Adobe Acrobat and Acrobat Reader across both Windows and macOS platforms. Exploitation requires user interaction—specifically, the victim must open a maliciously crafted PDF file.

Critical Impact

This vulnerability is actively exploited in the wild and has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog. Organizations must prioritize patching immediately as threat actors are actively targeting systems with malicious PDF documents.

Affected Products

• Adobe Acrobat DC (Continuous) versions prior to 23.003.20284
• Adobe Acrobat Reader DC (Continuous) versions prior to 23.003.20284
• Adobe Acrobat (Classic 2020) versions 20.005.30516 and earlier
• Adobe Acrobat Reader (Classic 2020) versions 20.005.30514 and earlier
• Microsoft Windows (as target platform)
• Apple macOS (as target platform)

Discovery Timeline

• September 13, 2023 - CVE-2023-26369 published to NVD
• October 23, 2025 - Last updated in NVD database

Technical Details for CVE-2023-26369

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), a memory corruption issue where an application writes data past the end or before the beginning of the intended buffer. In the context of Adobe Acrobat, this out-of-bounds write condition can be triggered when processing specially crafted PDF content, allowing an attacker to corrupt adjacent memory regions and potentially redirect program execution flow.

The exploitation requires local access through a malicious file that must be opened by the victim, making phishing campaigns and drive-by downloads likely attack vectors. Upon successful exploitation, an attacker gains code execution privileges equivalent to the current user, potentially allowing full system compromise if the user has administrative rights.

Root Cause

The root cause lies in improper bounds checking within Adobe Acrobat's PDF parsing and rendering engine. When processing certain malformed or specially crafted PDF elements, the application fails to properly validate buffer boundaries before write operations. This allows an attacker to craft a PDF document that triggers writes beyond allocated memory buffers, corrupting critical program data structures or injecting malicious code into executable memory regions.

Attack Vector

The attack vector requires user interaction through opening a malicious PDF file. Attackers typically deliver these weaponized documents through:

• Phishing emails with malicious PDF attachments
• Compromised websites hosting malicious PDF downloads
• Drive-by download attacks embedding PDF content
• Social engineering tactics encouraging users to open untrusted documents

Once the victim opens the malicious PDF in a vulnerable version of Adobe Acrobat or Acrobat Reader, the out-of-bounds write is triggered during document parsing, allowing arbitrary code execution with the privileges of the current user.

The vulnerability exploits the trust users place in PDF documents, which are commonly used in business contexts. The out-of-bounds write condition occurs during the processing of malformed PDF structures, where insufficient validation of input data allows memory corruption that can be leveraged to achieve code execution. For detailed technical information, refer to the Adobe Security Advisory APSB23-34.

Detection Methods for CVE-2023-26369

Indicators of Compromise

• Unusual Adobe Acrobat or Acrobat Reader process behavior including unexpected child process spawning
• PDF files with anomalous internal structures or embedded executable content
• Network connections initiated by Adobe Reader processes to unknown external hosts
• Memory access violations or application crashes when opening PDF documents
• Suspicious PowerShell or command prompt execution originating from AcroRd32.exe or Acrobat.exe

Detection Strategies

• Deploy endpoint detection and response (EDR) solutions to monitor for suspicious process chains originating from PDF readers
• Implement behavioral analysis to detect code execution attempts following PDF file opening events
• Configure YARA rules to identify malicious PDF structures associated with out-of-bounds write exploitation
• Monitor for exploitation indicators using SentinelOne's behavioral AI engine which can detect memory corruption exploitation in real-time

Monitoring Recommendations

• Enable detailed logging for Adobe Acrobat and Acrobat Reader application events
• Monitor file system activity for suspicious PDF downloads and temporary file creation patterns
• Track process creation events where parent processes are Adobe applications
• Implement network monitoring for data exfiltration attempts following PDF document access

How to Mitigate CVE-2023-26369

Immediate Actions Required

• Update Adobe Acrobat and Acrobat Reader to the latest patched versions immediately
• Block or quarantine suspicious PDF attachments at the email gateway
• Restrict execution of untrusted PDF documents in isolated sandbox environments
• Enable Protected View mode in Adobe Acrobat to limit JavaScript execution
• Deploy SentinelOne agents to detect and prevent exploitation attempts

Patch Information

Adobe has released security updates addressing this vulnerability in Security Bulletin APSB23-34. Organizations should update to the following versions or later:

• Adobe Acrobat DC (Continuous): Version 23.006.20320 or later
• Adobe Acrobat Reader DC (Continuous): Version 23.006.20320 or later
• Adobe Acrobat 2020 (Classic): Version 20.005.30524 or later
• Adobe Acrobat Reader 2020 (Classic): Version 20.005.30524 or later

Given this vulnerability is listed in the CISA Known Exploited Vulnerabilities Catalog, federal agencies and critical infrastructure organizations are required to remediate according to CISA deadlines.

Workarounds

• Enable Protected View mode in Adobe Acrobat preferences to open files from untrusted sources in a sandboxed environment
• Disable JavaScript in Adobe Reader through Edit > Preferences > JavaScript > uncheck "Enable Acrobat JavaScript"
• Use alternative PDF readers for untrusted documents until patching is complete
• Implement application allowlisting to control PDF reader execution

# Adobe Acrobat Protected View Configuration (Windows Registry)
# Enable Protected View for all files
reg add "HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\DC\TrustManager" /v iProtectedView /t REG_DWORD /d 2 /f

# Disable JavaScript execution
reg add "HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\DC\JSPrefs" /v bEnableJS /t REG_DWORD /d 0 /f