CVE-2025-64787: Adobe Acrobat Auth Bypass Vulnerability

CVE-2025-64787 Overview

CVE-2025-64787 is an Improper Verification of Cryptographic Signature vulnerability [CWE-347] affecting Adobe Acrobat and Acrobat Reader. The flaw allows an attacker to bypass cryptographic protections and gain limited unauthorized write access on affected systems. Successful exploitation requires user interaction with a crafted cryptographic signature. Affected versions include Acrobat Reader 24.001.30264, 20.005.30793, 25.001.20982, 24.001.30273, 20.005.30803, and earlier releases on both Windows and macOS. Adobe addressed the issue in security bulletin APSB25-119.

Critical Impact

An attacker can bypass signature verification to achieve limited unauthorized write access when a user interacts with a malicious signed document.

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 CVE-2025-64787 published to NVD
• 2026-09-25 - Last updated in NVD database

Technical Details for CVE-2025-64787

Vulnerability Analysis

The vulnerability resides in how Adobe Acrobat and Acrobat Reader validate cryptographic signatures associated with PDF content. The product fails to properly verify signature integrity, which allows a crafted signature to be accepted as trusted. Once accepted, the signature enables an attacker to bypass a security feature that normally restricts document behavior. The resulting access is limited to integrity impact, meaning an attacker can modify a bounded set of data but cannot read confidential information or crash the application. The flaw is local in scope and requires the victim to open or interact with a malicious document in Acrobat.

Root Cause

The root cause is improper verification of a cryptographic signature, categorized under [CWE-347]. Acrobat's signature validation logic does not sufficiently check the authenticity or binding of the signature to the signed data. This allows a mismatched or forged signature to be treated as valid, undermining downstream trust decisions.

Attack Vector

Exploitation requires local attack conditions combined with user interaction. An attacker crafts a PDF or signed object with a manipulated cryptographic signature and delivers it through email, a file share, or a website. When the user opens the document in Acrobat or Reader and interacts with the signature prompt, the application accepts the forged signature and permits the restricted write operation. No elevated privileges are required to deliver the payload. See the Adobe Acrobat Security Bulletin APSB25-119 for technical details.

Detection Methods for CVE-2025-64787

Indicators of Compromise

• Unexpected PDF files containing digital signatures from unknown or untrusted issuers opened by end users
• Modifications to files or application-managed data following interaction with a signed PDF
• Acrobat or Reader process writing to paths outside normal document save locations

Detection Strategies

• Inspect email gateways and web proxies for inbound PDF attachments containing embedded signatures from unverified certificate authorities
• Correlate AcroRd32.exe or Acrobat.exe process activity with file-write events in non-standard directories
• Alert on execution of vulnerable Acrobat and Reader builds listed in APSB25-119 across the environment

Monitoring Recommendations

• Maintain an inventory of installed Acrobat and Reader versions and flag hosts running 24.001.30264, 20.005.30793, 25.001.20982, 24.001.30273, 20.005.30803, or earlier
• Monitor endpoint logs for abnormal child processes or file-system changes initiated by Acrobat following a signature trust dialog
• Capture Windows and macOS audit telemetry for file writes performed by Acrobat into user-profile and configuration directories

How to Mitigate CVE-2025-64787

Immediate Actions Required

• Apply the Adobe updates referenced in APSB25-119 to all Acrobat and Reader installations
• Prioritize patching endpoints that routinely process externally sourced signed PDFs, such as legal, finance, and HR workstations
• Instruct users to avoid trusting signature prompts on unsolicited documents until updates are deployed

Patch Information

Adobe released fixes for Acrobat and Acrobat Reader on both Windows and macOS. Administrators should upgrade to the versions specified in the Adobe Acrobat Security Bulletin APSB25-119. Both Continuous and Classic tracks receive updated builds.

Workarounds

• Disable automatic signature validation in Acrobat preferences until patches are applied
• Use Protected View or Protected Mode to limit the privileges available to Acrobat when opening untrusted documents
• Restrict PDF handling to a hardened viewer or sandboxed environment for documents originating outside the organization

# Example: enforce Protected Mode and disable JavaScript via Windows registry
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\Privileged" /v bProtectedMode /t REG_DWORD /d 1 /f
reg add "HKCU\Software\Adobe\Acrobat Reader\DC\JSPrefs" /v bEnableJS /t REG_DWORD /d 0 /f