CVE-2025-64786: Adobe Acrobat Auth Bypass Vulnerability

CVE-2025-64786 Overview

CVE-2025-64786 is an Improper Verification of Cryptographic Signature vulnerability [CWE-347] affecting Adobe Acrobat and Acrobat Reader. The flaw impacts versions 24.001.30264, 20.005.30793, 25.001.20982, 24.001.30273, 20.005.30803 and earlier on both Windows and macOS. An attacker can leverage the weakness to achieve a security feature bypass and obtain limited unauthorized write access. Exploitation requires local user interaction with a cryptographic signature, which constrains attack scalability. Adobe published the fix in security bulletin APSB25-119.

Critical Impact

Attackers can bypass cryptographic signature verification in Acrobat and Acrobat Reader to gain limited unauthorized write access when a user interacts with a crafted signed PDF.

Affected Products

• Adobe Acrobat and Acrobat DC (Classic and Continuous tracks)
• Adobe Acrobat Reader and Acrobat Reader DC (Classic and Continuous tracks)
• Microsoft Windows and Apple macOS installations of the above

Discovery Timeline

• 2025-12-09 - CVE-2025-64786 published to NVD
• 2026-09-25 - Last updated in NVD database

Technical Details for CVE-2025-64786

Vulnerability Analysis

The vulnerability lies in how Adobe Acrobat and Acrobat Reader verify cryptographic signatures on PDF documents. The signature validation routine fails to properly enforce verification constraints, allowing a crafted signed PDF to pass checks it should fail. This results in a security feature bypass rather than code execution. The attacker gains limited unauthorized write access within the application's trust boundary. Attack requires local file handling and user interaction with the signature workflow, limiting remote exploitation potential.

Root Cause

The issue is categorized under CWE-347: Improper Verification of Cryptographic Signature. Acrobat's signature verification logic does not fully validate signed content, allowing modifications or trust decisions that the signer never authorized. The result is that integrity guarantees normally provided by digital signatures are not enforced for the affected content paths.

Attack Vector

An attacker must deliver a specially crafted PDF containing a manipulated cryptographic signature to a target user. The user must open the document and interact with the signature, for example by trusting or validating the signed content. Successful exploitation yields limited unauthorized write access scoped to the application. Because the vector is local and user-interactive, phishing and social engineering remain the most realistic delivery methods.

No verified exploit code or public proof-of-concept is available at this time. Refer to the Adobe Acrobat Security Bulletin APSB25-119 for vendor technical details.

Detection Methods for CVE-2025-64786

Indicators of Compromise

• PDF files containing malformed or anomalous digital signature structures opened by Acrobat or Reader.
• Unexpected file writes or modifications occurring in the context of AcroRd32.exe or Acrobat.exe processes.
• User reports of signed PDFs displaying trust status inconsistent with the document source.

Detection Strategies

• Monitor endpoints for Acrobat and Reader processes performing write operations to unusual directories outside their normal cache paths.
• Inspect PDF attachments from email gateways for abnormal signature dictionary structures and unverifiable certificate chains.
• Correlate user interaction with signature prompts against subsequent file system activity from Adobe processes.

Monitoring Recommendations

• Enable detailed process and file telemetry on endpoints running Adobe Acrobat or Reader across Windows and macOS.
• Track installed Acrobat and Reader versions through software inventory to identify hosts still running vulnerable builds.
• Alert on PDF documents containing digital signatures that fail strict external validation when scanned at the mail gateway.

How to Mitigate CVE-2025-64786

Immediate Actions Required

• Apply the updates from Adobe Security Bulletin APSB25-119 to all affected Acrobat and Reader installations.
• Inventory endpoints to identify hosts running the vulnerable versions listed in the advisory and prioritize patching.
• Instruct users to avoid interacting with signed PDFs from untrusted sources until patches are deployed.

Patch Information

Adobe addressed the vulnerability in the updates documented in bulletin APSB25-119. Administrators should deploy the fixed versions through the Adobe Admin Console, enterprise software distribution tools, or the built-in updater. Both Classic and Continuous tracks on Windows and macOS require updating.

Workarounds

• Enforce Protected View or Protected Mode in Acrobat and Reader to limit the impact of untrusted documents.
• Block or quarantine inbound PDF attachments with digital signatures that fail validation at the email security gateway.
• Restrict write permissions on sensitive directories accessible to the user context running Acrobat.

# Example: enforce Protected View for all files on Windows via registry
reg add "HKLM\SOFTWARE\Policies\Adobe\Acrobat Reader\DC\FeatureLockDown" /v bProtectedMode /t REG_DWORD /d 1 /f
reg add "HKLM\SOFTWARE\Policies\Adobe\Acrobat Reader\DC\FeatureLockDown" /v iProtectedView /t REG_DWORD /d 2 /f