CVE-2024-39423: Adobe Acrobat RCE Vulnerability

CVE-2024-39423 Overview

CVE-2024-39423 is an out-of-bounds write vulnerability [CWE-787] affecting Adobe Acrobat and Acrobat Reader on Windows and macOS. The flaw impacts Acrobat Reader versions 20.005.30636, 24.002.20965, 24.002.20964, 24.001.30123, and earlier releases across both the Classic and Continuous tracks. Successful exploitation allows arbitrary code execution in the context of the current user. Adobe published fixes in security bulletin APSB24-57.

Critical Impact
An attacker who convinces a user to open a crafted PDF file can execute arbitrary code with the privileges of the current user, enabling malware installation, credential theft, or lateral movement.

Affected Products

Adobe Acrobat and Acrobat DC (Classic and Continuous tracks) at or below the listed versions
Adobe Acrobat Reader and Acrobat Reader DC (Classic and Continuous tracks) at or below the listed versions
Microsoft Windows and Apple macOS installations running the affected Acrobat builds

Discovery Timeline

2024-08-14 - CVE-2024-39423 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-39423

Vulnerability Analysis

The vulnerability is an out-of-bounds write [CWE-787] within Adobe Acrobat's PDF parsing and rendering logic. When Acrobat processes a malformed object inside a crafted PDF, the application writes attacker-controlled data past the bounds of an allocated buffer. This corruption of adjacent memory can overwrite function pointers, virtual tables, or heap metadata used by later execution paths. An attacker who shapes the heap layout precisely can redirect control flow and achieve arbitrary code execution in the context of the user opening the file. The issue requires user interaction, as a victim must open the malicious document, but no authentication or elevated privileges are needed. The EPSS probability of approximately 3.9% (89th percentile) reflects meaningful attacker interest relative to other CVEs.

Root Cause

The root cause is missing or incorrect boundary validation during deserialization of a specific PDF structure. The parser trusts a length or index value taken from the file without verifying it against the destination buffer size. As a result, attacker-controlled bytes are copied beyond the intended memory region.

Attack Vector

Exploitation is local and requires user interaction. An attacker delivers a weaponized PDF via email attachment, chat, drive-by download, or a compromised website. When the victim opens the file with a vulnerable Acrobat build, the out-of-bounds write triggers during parsing, and code execution occurs under the user's account.

No verified public proof-of-concept code is available for CVE-2024-39423. Refer to the Adobe Acrobat Security Advisory APSB24-57 for vendor technical guidance.

Detection Methods for CVE-2024-39423

Indicators of Compromise

Acrobat processes (Acrobat.exe, AcroRd32.exe, AdobeAcrobat) spawning child processes such as cmd.exe, powershell.exe, wscript.exe, or bash
Unexpected outbound network connections initiated by Acrobat processes shortly after a PDF is opened
Crashes or Windows Error Reporting entries referencing Acrobat modules following interaction with an emailed or downloaded PDF
New files, scheduled tasks, or registry Run keys created by an Acrobat process

Detection Strategies

Alert on Acrobat processes writing executable content to disk or loading unsigned DLLs from user-writable paths
Detect PDF files containing anomalously large or malformed stream length fields via mail gateway and endpoint inspection
Correlate PDF-opening events with subsequent process, file, or network activity to identify exploitation chains

Monitoring Recommendations

Enforce process-lineage telemetry from Acrobat binaries across all Windows and macOS endpoints
Ingest EDR and email gateway logs into a centralized data lake to hunt for suspicious PDF delivery patterns
Track Acrobat version inventory to identify unpatched hosts and prioritize remediation

How to Mitigate CVE-2024-39423

Immediate Actions Required

Update Adobe Acrobat and Acrobat Reader to the fixed builds listed in Adobe security bulletin APSB24-57
Restrict opening of PDF files received from untrusted sources until patching is complete
Enable Protected View and Protected Mode / Sandbox in Acrobat to constrain exploitation impact
Confirm that endpoint identification and response is active on all systems that render PDFs

Patch Information

Adobe released updated versions of Acrobat and Acrobat Reader that address CVE-2024-39423. Administrators should deploy the versions specified in the Adobe Acrobat Security Advisory APSB24-57 through the Adobe Update Manager, enterprise software distribution tools, or the vendor's MSI/PKG installers.

Workarounds

Configure Acrobat to run in Protected View for files from the internet and other unsafe locations
Block inbound PDF attachments from untrusted external senders at the mail gateway when feasible
Set an alternate default PDF handler on high-risk hosts until the update is applied

bash

# Windows: verify installed Acrobat Reader version and enforce Protected View via registry
reg query "HKLM\SOFTWARE\Adobe\Acrobat Reader\DC\Installer" /v VersionMax

reg add "HKCU\Software\Adobe\Acrobat Reader\DC\TrustManager" /v iProtectedView /t REG_DWORD /d 2 /f
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\Privileged" /v bProtectedMode /t REG_DWORD /d 1 /f