Adobe Acrobat and Reader Use-After-Free Remote Code Execution Vulnerability (CVE-2023-21608) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTAdobe Acrobat and Reader versions 22.003.20282 (and earlier), 22.003.20281 (and earlier), and 20.005.30418 (and earlier)
Successful exploitation could lead to arbitrary code execution in the context of the current user when a victim opens a crafted malicious PDF
Immediately apply the official Adobe security patches to upgrade to the latest secure versions
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official Adobe security update (APSB23-01) immediately. In enterprise environments, you can query installed versions and deploy patches using the following PowerShell commands:
# Query installed Adobe Acrobat/Reader versions via Registry
$regPath = 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*'
Get-ItemProperty $regPath | Where-Object { $_.DisplayName -like '*Adobe Acrobat*' } | Select-Object DisplayName, DisplayVersion2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, enforce Adobe's Protected Mode and disable JavaScript execution within PDF documents to mitigate the attack vector.
# Force enable Protected Mode in Adobe Reader via Registry
New-ItemProperty -Path 'HKCU:\Software\Adobe\Acrobat Reader\DC\Privileged' -Name 'bProtectedMode' -Value 1 -PropertyType DWORD -Force
# Disable JavaScript execution in Adobe Reader
New-ItemProperty -Path 'HKCU:\Software\Adobe\Acrobat Reader\DC\JSPrefs' -Name 'bEnableJS' -Value 0 -PropertyType DWORD -Force3. Log Audit & IoC Verification Commands
Monitor for suspicious child processes spawned by Adobe Acrobat or Reader, which is a common indicator of successful exploitation (e.g., Acrobat spawning cmd.exe or powershell.exe).
# Detect anomalous child processes spawned by Adobe Acrobat/Reader
Get-CimInstance Win32_Process | Where-Object { $_.ParentProcessId -in (Get-Process -Name 'AcroRd32', 'Acrobat' -ErrorAction SilentlyContinue).Id } | Select-Object ProcessId, Name, CommandLineBlock Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2023-21608) is a critical Use-After-Free (UAF) flaw in Adobe Acrobat and Reader. It occurs when the application processes specific objects or JavaScript APIs within a PDF document and fails to properly clear pointers to memory locations that have already been deallocated. This allows an attacker to reference the dangling pointer, causing memory corruption and hijacking the execution flow.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker crafts a malicious PDF file containing a specific structure designed to trigger the UAF condition. The attacker then delivers this file to the target user via social engineering, phishing emails, or malicious web downloads. Once the victim opens the file using a vulnerable version of Adobe Acrobat or Reader, the application's parsing engine triggers the memory corruption, executing the attacker's embedded shellcode with the privileges of the logged-in user.
3. Infrastructure & Business Impact
This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. With an EPSS score of approximately 59.4%, the likelihood of exploitation attempts remains extremely high. Successful exploitation allows attackers to compromise endpoint workstations, establish initial access within the corporate network, exfiltrate sensitive documents, or deploy ransomware.
Official Vendor Advisories & References
Adobe Acrobat Reader versions 22.003.20282 (and earlier), 22.003.20281 (and earlier) and 20.005.30418 (and earlier) are affected by a Use After Free vulnerability that could result in arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
Frequently Asked SecOps Questions (CVE-2023-21608)
FAQQ1. How critical is CVE-2023-21608 and is it actively exploited in the wild?
CVE-2023-21608 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 59.4%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2023-21608?
Primary impacted vendors include adobe across acrobat, acrobat reader. Scope summary: Adobe Acrobat Reader and Acrobat Continuous (22.003.20282 and earlier, 22.003.20281 and earlier), Classic 2020 (20.005.30418 and earlier)
Q3. What temporary mitigations or workarounds exist for CVE-2023-21608 before patching?
[Mitigation] Immediately apply the official Adobe security patches to upgrade to the latest secure versions Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2023-21608
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