CVE-2026-21355: DNG SDK Information Disclosure Flaw

CVE-2026-21355 Overview

CVE-2026-21355 is an out-of-bounds read vulnerability affecting Adobe DNG SDK versions 1.7.1 2410 and earlier. This memory corruption flaw could allow an attacker to disclose sensitive information stored in memory by leveraging improper boundary checks during file processing. Exploitation requires user interaction, specifically that a victim must open a maliciously crafted file.

Critical Impact

Successful exploitation could lead to sensitive memory exposure, potentially disclosing confidential data, cryptographic keys, or other protected information from the application's memory space.

Affected Products

• Adobe DNG SDK versions 1.7.1 2410 and earlier
• Applications utilizing vulnerable DNG SDK components
• Software processing Digital Negative (DNG) image files with affected SDK versions

Discovery Timeline

• 2026-02-10 - CVE-2026-21355 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2026-21355

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-Bounds Read), a memory safety issue where the application reads data beyond the boundaries of an allocated buffer. In the context of the DNG SDK, this occurs during the parsing or processing of Digital Negative image files. When a malformed DNG file is processed, the SDK fails to properly validate buffer boundaries, allowing read operations to access memory locations outside the intended data structure.

The local attack vector indicates that an attacker must deliver a malicious file to the victim's system, and the victim must actively open or process this file using an application that relies on the vulnerable DNG SDK. This user interaction requirement reduces the likelihood of automated exploitation but remains a significant risk in targeted attacks or when distributed through social engineering campaigns.

Root Cause

The root cause of CVE-2026-21355 lies in insufficient bounds checking within the DNG SDK's file parsing routines. When processing metadata or image data from a DNG file, the SDK reads offsets or length values from the file without adequately validating that subsequent read operations remain within allocated buffer boundaries. This allows crafted input values to cause the application to read beyond buffer limits.

Attack Vector

An attacker exploiting CVE-2026-21355 would craft a malicious DNG file containing specially constructed metadata or image data structures designed to trigger the out-of-bounds read condition. The attack scenario typically involves:

1. The attacker creates a malformed DNG file with manipulated offset or length fields
2. The malicious file is delivered to the victim via email attachment, web download, or other file transfer mechanisms
3. The victim opens the file using an application that utilizes the vulnerable DNG SDK
4. During file parsing, the SDK reads memory beyond allocated buffers
5. Sensitive information from adjacent memory regions is exposed to the attacker

This vulnerability does not allow code execution or modify data integrity but focuses solely on information disclosure through memory exposure.

Detection Methods for CVE-2026-21355

Indicators of Compromise

• Unusual DNG files with abnormal metadata structures or corrupted headers
• Application crashes or unexpected behavior when processing DNG image files
• Memory access violations or exceptions during image file operations
• Suspicious DNG files received from untrusted sources

Detection Strategies

• Monitor applications utilizing DNG SDK for abnormal memory access patterns
• Implement file integrity monitoring for DNG files entering the environment
• Deploy endpoint detection solutions capable of identifying memory disclosure attempts
• Analyze application logs for parsing errors related to DNG file processing

Monitoring Recommendations

• Enable verbose logging for applications processing DNG image files
• Monitor for unexpected memory read operations in DNG SDK-dependent processes
• Track file downloads and email attachments containing DNG file extensions
• Implement behavior-based detection for applications exhibiting signs of exploitation

How to Mitigate CVE-2026-21355

Immediate Actions Required

• Update Adobe DNG SDK to the latest patched version as specified in APSB26-23
• Audit systems to identify all applications utilizing affected DNG SDK versions
• Restrict processing of DNG files from untrusted sources until patches are applied
• Educate users about the risks of opening unsolicited DNG image files

Patch Information

Adobe has released a security update addressing this vulnerability. Organizations should consult the Adobe Security Advisory APSB26-23 for detailed patch information and download instructions. The patch implements proper bounds validation for buffer read operations during DNG file processing.

Workarounds

• Block or quarantine DNG files at email gateways and web proxies until systems are patched
• Disable automatic preview or thumbnail generation for DNG files in affected applications
• Use application sandboxing to limit the impact of potential memory disclosure
• Implement strict file type policies that restrict DNG file processing to trusted sources only

# Example: Restrict DNG file processing at the gateway level
# Block DNG files at email gateway (example configuration)
# Add .dng extension to blocked attachment types in your mail security policy
# Configure web proxy to scan or block DNG file downloads from untrusted domains