CVE-2025-64787: 
Adobe Acrobat Reader Continuous vulnerability analysis and mitigation

CVE-2025-64787 is an Improper Verification of Cryptographic Signature vulnerability (CWE-347) in Adobe Acrobat and Acrobat Reader that allows an attacker to bypass cryptographic protections and gain limited unauthorized write access. Affected versions include Acrobat Reader and Acrobat DC (Continuous track) prior to 25.001.20997, Acrobat Classic 2024 prior to 24.001.30307/30308, and Acrobat/Acrobat Reader Classic 2020 prior to 20.005.30838. The vulnerability was published on December 9, 2025, and a patch was made available via Adobe Security Bulletin APSB25-119 on December 12, 2025. It carries a CVSS v3.1 base score of 3.3 (Low) (Adobe Advisory, Feedly).

The root cause is classified as CWE-347 (Improper Verification of Cryptographic Signature), meaning the application fails to properly validate cryptographic signatures on PDF documents or related data structures. This flaw maps to CAPEC-475 (Signature Spoofing by Improper Validation), where an attacker crafts or manipulates a document with an invalid or forged signature that the application incorrectly accepts as valid. Exploitation requires user interaction — specifically, a user must open or interact with a maliciously crafted PDF containing a manipulated cryptographic signature. The attack vector is local (AV:L), requiring the attacker to deliver a crafted file to the victim's system, with no privileges required on the attacker's part (Adobe Advisory, Feedly).

Successful exploitation results in a security feature bypass, specifically circumventing cryptographic signature verification in Adobe Acrobat/Reader, and grants the attacker limited unauthorized write access. The confidentiality impact is none, and availability is unaffected; the primary risk is to integrity — an attacker could compromise the trustworthiness of cryptographically signed PDF documents, potentially causing users or systems to accept tampered documents as authentic. The scope is unchanged and the impact is constrained to the local system context, limiting the potential for lateral movement or broad data exposure (Adobe Advisory, Feedly).

1. Craft a malicious PDF: An attacker creates or modifies a PDF document with a manipulated or forged cryptographic signature that exploits the improper verification logic in Adobe Acrobat/Reader.
2. Deliver the file: The attacker delivers the crafted PDF to the target user via email, file share, or web download, relying on social engineering to prompt the user to open it.
3. User interaction: The victim opens the PDF in a vulnerable version of Adobe Acrobat or Acrobat Reader, triggering the signature verification process.
4. Bypass signature verification: The application incorrectly validates the forged signature, accepting the document as cryptographically authentic when it is not.
5. Achieve limited write access: The attacker leverages the bypass to gain limited unauthorized write access to the document or local system resources, potentially modifying document content that appears signed and trusted (Adobe Advisory, Feedly).

• File System: Unexpected modifications to PDF files that carry digital signatures; presence of PDF files with malformed or anomalous signature structures in user download or temp directories.
• Logs: Adobe Acrobat/Reader application logs showing signature validation events on documents from untrusted or external sources; repeated opening of PDFs with signature-related warnings dismissed by the user.
• Process: Adobe Acrobat/Reader processes performing unexpected file write operations following the opening of a PDF document.

Adobe has released patches via Security Bulletin APSB25-119 (December 2025). Users should update to the following fixed versions: Acrobat DC and Acrobat Reader DC (Continuous) to 25.001.20997 or later; Acrobat Classic 2024 to 24.001.30307/30308 or later; Acrobat and Acrobat Reader Classic 2020 to 20.005.30838 or later. As interim measures, organizations should restrict local access to PDF applications, implement application whitelisting, and advise users to exercise caution when opening PDFs from untrusted sources. Adobe's automatic update mechanism can be used to apply patches promptly (Adobe Advisory).

The vulnerability was covered as part of Adobe's December 2025 Patch Tuesday cycle, with Sophos noting it as part of a significant end-of-year patch release (Sophos Blog). Security news outlets including CyberSecurityNews, CyberPress, and UnderCodeNews reported on the broader Adobe Acrobat/Reader vulnerability batch, though CVE-2025-64787 itself received limited individual attention given its low CVSS score. Community sentiment reflects routine patch urgency rather than alarm, consistent with the vulnerability's low severity rating and absence of active exploitation.