CVE-2026-34667: Adobe C2PA Integer Underflow DoS Flaw

CVE-2026-34667 Overview

CVE-2026-34667 is an integer underflow vulnerability [CWE-191] affecting Adobe's Content Authenticity Initiative (CAI) Content Credentials libraries. The flaw impacts c2pa (Rust) versions 0.78.2 and earlier, and c2pa-web (Node.js) versions 0.7.0 and earlier. An attacker with local access can trigger an arithmetic wraparound condition that crashes the application, producing a denial-of-service (DoS) state. Exploitation requires no user interaction and no privileges. The vulnerability does not expose confidentiality or integrity, but availability impact is high. Adobe addressed the issue in security bulletin APSB26-53.

Critical Impact

Local attackers can crash applications using the C2PA Content Credentials SDK without authentication or user interaction, disrupting content provenance verification workflows.

Affected Products

• Adobe c2pa (Rust SDK) versions 0.78.2 and earlier
• Adobe c2pa-web (Node.js SDK) versions 0.7.0 and earlier
• Applications embedding the CAI Content Credentials SDK for media provenance validation

Discovery Timeline

• 2026-05-12 - CVE-2026-34667 published to NVD
• 2026-05-15 - Last updated in NVD database

Technical Details for CVE-2026-34667

Vulnerability Analysis

The vulnerability resides in the C2PA Content Credentials parsing logic, which handles signed media assertions used to verify the provenance and authenticity of digital content. During processing of attacker-controlled input, an arithmetic operation produces a value below the minimum representable bound for its integer type. The result wraps around to a large unsigned value, which is subsequently used in size calculations or memory access logic. This leads to an unrecoverable runtime error and forces the host application to terminate. The attack vector is local, meaning the attacker must supply a crafted asset to a process invoking the SDK. The flaw affects both the Rust crate and the Node.js binding, indicating the underlying defect resides in shared parsing logic.

Root Cause

The root cause is an unchecked subtraction or decrement operation on an unsigned integer used during C2PA manifest or assertion processing. When input data causes the operand to fall below zero, the value wraps to a near-maximum unsigned integer. Subsequent buffer length checks or allocation calls fail, terminating the process. This pattern aligns with CWE-191: Integer Underflow (Wrap or Wraparound).

Attack Vector

An attacker crafts a malformed C2PA-signed asset, such as a manipulated image or video container with corrupted manifest metadata. When a vulnerable application loads the file through the c2pa or c2pa-web SDK, the parser triggers the underflow and the process crashes. Repeated submission of the asset prevents the application from completing provenance verification, disrupting downstream content workflows.

No public exploit code or proof-of-concept is available at the time of publication. Refer to the Adobe Security Bulletin APSB26-53 for vendor technical details.

Detection Methods for CVE-2026-34667

Indicators of Compromise

• Repeated abnormal termination of processes linked against the c2pa Rust crate or c2pa-web Node.js package
• Crash dumps referencing C2PA manifest parsing functions or arithmetic exceptions in the SDK call stack
• Unexpected ingestion of malformed media assets immediately preceding application failure

Detection Strategies

• Monitor for crash signatures and exit codes from services that load Content Credentials assets
• Inspect inbound media files for malformed C2PA manifests using validation tooling prior to SDK processing
• Correlate application restart events with file ingestion logs to identify malicious asset submissions

Monitoring Recommendations

• Enable verbose logging on applications that invoke c2pa or c2pa-web and forward logs to a centralized analytics platform
• Track SDK version inventory across build pipelines to confirm affected packages have been removed
• Alert on repeated process crashes within short time windows for services handling user-supplied content

How to Mitigate CVE-2026-34667

Immediate Actions Required

• Upgrade the Adobe c2pa Rust crate to a version newer than 0.78.2 as published in APSB26-53
• Upgrade the Adobe c2pa-web Node.js package to a version newer than 0.7.0
• Audit application dependency manifests (Cargo.toml, package.json) to confirm vulnerable versions are not pinned
• Restrict local access to systems that process untrusted C2PA-signed media

Patch Information

Adobe released fixed versions of the CAI Content Credentials SDK as documented in Adobe Security Bulletin APSB26-53. Apply the vendor-supplied updates and rebuild applications that statically link the SDK.

Workarounds

• Validate media assets through a sandboxed pre-processor before passing them to the C2PA SDK
• Implement automatic restart and rate-limiting on services that perform Content Credentials verification to reduce DoS dwell time
• Limit acceptance of C2PA-signed assets to trusted sources until SDK upgrades are completed