CVE-2024-39426: Adobe Acrobat RCE Vulnerability

CVE-2024-39426 Overview

CVE-2024-39426 is an out-of-bounds read vulnerability [CWE-125] affecting Adobe Acrobat and Acrobat Reader. Adobe Acrobat versions 20.005.30636, 24.002.20965, 24.002.20964, 24.001.30123 and earlier are affected. The flaw occurs when the application parses a crafted file, causing a read past the end of an allocated memory structure. An attacker can leverage this issue to execute code in the context of the current user. Exploitation requires user interaction because a victim must open a malicious file. The vulnerability affects Acrobat installations on both Microsoft Windows and Apple macOS platforms.

Critical Impact
Successful exploitation allows arbitrary code execution in the context of the current user through a maliciously crafted PDF file.

Affected Products

Adobe Acrobat and Acrobat DC (Classic and Continuous tracks) versions 20.005.30636, 24.002.20965, 24.002.20964, 24.001.30123 and earlier
Adobe Acrobat Reader and Acrobat Reader DC (Classic and Continuous tracks) at the same versions
Microsoft Windows and Apple macOS installations of the affected products

Discovery Timeline

2024-08-14 - CVE-2024-39426 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-39426

Vulnerability Analysis

The vulnerability is classified as an out-of-bounds read [CWE-125] within the file parsing components of Adobe Acrobat and Reader. When the application processes a crafted PDF, it reads data past the boundary of an allocated memory structure. This adjacent memory may contain pointers, object metadata, or heap chunk headers that influence subsequent processing.

An attacker who controls the shape of the crafted file can influence which memory the parser dereferences. Combined with heap grooming, the out-of-bounds read becomes a primitive that can be chained to achieve arbitrary code execution in the context of the current user.

Because the attack vector is local and requires user interaction, exploitation typically occurs through social engineering. A victim opens a weaponized PDF delivered by email, web download, or shared file storage.

Root Cause

The root cause is missing or insufficient bounds checking during parsing of specific PDF structures. The parser trusts length or offset fields from the file without validating them against the size of the underlying allocation. Adobe has not disclosed the specific file element or parsing routine responsible for the flaw.

Attack Vector

Exploitation follows a client-side attack pattern. The attacker crafts a malicious PDF and delivers it to the target. When the victim opens the file in a vulnerable version of Acrobat or Reader, the parser triggers the out-of-bounds read. The attacker gains code execution with the privileges of the user running the application.

See the Adobe Acrobat Security Advisory APSB24-57 for vendor technical details. No public proof-of-concept exploit code is currently listed for this CVE.

Detection Methods for CVE-2024-39426

Indicators of Compromise

Unexpected child processes spawned by Acrobat.exe or AcroRd32.exe, such as cmd.exe, powershell.exe, or scripting hosts
Acrobat or Reader processes crashing repeatedly when opening specific PDF files, potentially indicating exploitation attempts
PDF files arriving from untrusted senders that contain embedded JavaScript, unusual object streams, or malformed cross-reference tables
Outbound network connections initiated by Acrobat processes to unfamiliar domains or IP addresses shortly after a PDF is opened

Detection Strategies

Monitor process ancestry for Acrobat and Reader binaries and alert on execution of interpreters or LOLBins as child processes
Deploy YARA rules that identify malformed PDF structures known to trigger parser edge cases
Correlate Windows Error Reporting or macOS crash reports referencing Acrobat modules with recent file open activity
Inspect email gateways and web proxies for PDF attachments with anomalous object counts, stream sizes, or embedded active content

Monitoring Recommendations

Enable command-line and process creation logging (Windows Event ID 4688, Sysmon Event ID 1) on user endpoints
Track file writes made by Acrobat processes to sensitive directories such as %APPDATA%, Startup, or user profile locations
Alert on Acrobat processes loading unsigned DLLs or accessing memory in unusual ways that suggest exploitation

How to Mitigate CVE-2024-39426

Immediate Actions Required

Update Adobe Acrobat and Acrobat Reader to the fixed versions listed in Adobe security bulletin APSB24-57 across all Windows and macOS endpoints
Restrict opening of PDF files from untrusted sources and enforce sender verification through email security controls
Enable Protected Mode and Protected View in Acrobat and Reader to sandbox PDF rendering
Inventory endpoints running vulnerable Acrobat versions and prioritize remediation for high-value users

Patch Information

Adobe addressed CVE-2024-39426 in the security update documented in Adobe Acrobat Security Advisory APSB24-57. Administrators should deploy the updated Acrobat and Reader builds through Adobe Update Manager, SCCM, Intune, Jamf, or equivalent patch management tooling. Verify installed versions post-deployment to confirm remediation.

Workarounds

Disable JavaScript execution within Acrobat and Reader through the application preferences or enterprise policy
Configure Acrobat to block PDF attachments and untrusted file types via the Trust Manager
Use application allowlisting to restrict which processes Acrobat can spawn, blocking common post-exploitation binaries
Route inbound PDFs through a content disarm and reconstruction (CDR) gateway before delivery to users

bash

# Example Windows registry configuration to disable JavaScript in Acrobat Reader DC
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\JSPrefs" /v bEnableJS /t REG_DWORD /d 0 /f

# Enable Protected View for all files
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\TrustManager" /v iProtectedView /t REG_DWORD /d 2 /f