CVE-2025-63095: hello-video-codec DoS Vulnerability

CVE-2025-63095 Overview

CVE-2025-63095 is an improper input validation vulnerability affecting the BitstreamWriter::write_bits() function in Tempus Ex hello-video-codec version 0.1.0. This vulnerability allows attackers to cause a Denial of Service (DoS) condition by supplying specially crafted input to the affected function. The vulnerability exists in the bitstream processing component of the video codec library.

Critical Impact

Attackers can exploit this improper input validation flaw to trigger a DoS condition, potentially disrupting video processing services and applications that depend on the hello-video-codec library.

Affected Products

• Tempus Ex hello-video-codec v0.1.0
• Applications utilizing the hello-video-codec library for video processing
• Systems implementing the BitstreamWriter::write_bits() function from the vulnerable version

Discovery Timeline

• 2025-12-01 - CVE-2025-63095 published to NVD
• 2025-12-02 - Last updated in NVD database

Technical Details for CVE-2025-63095

Vulnerability Analysis

This vulnerability is classified under CWE-20 (Improper Input Validation), indicating that the BitstreamWriter::write_bits() function fails to properly validate input before processing. The vulnerability has been assigned a CVSS v3.1 score of 6.5 (MEDIUM) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

The CVSS metrics indicate:

• Attack Vector (AV:N): Network-accessible exploitation
• Attack Complexity (AC:L): Low complexity required
• Privileges Required (PR:N): No authentication needed
• User Interaction (UI:R): Requires user interaction
• Scope (S:U): Unchanged scope
• Confidentiality Impact (C:N): No confidentiality impact
• Integrity Impact (I:N): No integrity impact
• Availability Impact (A:H): High availability impact

The EPSS (Exploit Prediction Scoring System) probability is 0.041% with a percentile of 12.348, indicating a relatively low probability of exploitation in the wild.

Root Cause

The root cause of CVE-2025-63095 lies in the BitstreamWriter::write_bits() function within the src/bitstream.rs source file. The function does not adequately validate input parameters before processing bitstream data, allowing malformed or malicious input to trigger unexpected behavior leading to a denial of service condition.

The vulnerable code is located in the bitstream handling module of the hello-video-codec library. When processing crafted input that violates expected parameter boundaries or data formats, the function fails to handle edge cases gracefully, resulting in service disruption.

Attack Vector

The attack vector for CVE-2025-63095 is network-based, meaning an attacker can potentially exploit this vulnerability remotely. The attack requires user interaction, such as opening a maliciously crafted video file or processing attacker-controlled media content.

An attacker would craft malicious input designed to exploit the improper validation in the BitstreamWriter::write_bits() function. When a victim application processes this crafted input using the vulnerable library version, it triggers the DoS condition, causing the application to become unresponsive or crash.

For technical details regarding the vulnerability mechanism, refer to the security research gist and the vulnerable source code.

Detection Methods for CVE-2025-63095

Indicators of Compromise

• Application crashes or hangs when processing specific video files or bitstream data
• Unexpected resource consumption spikes in processes utilizing hello-video-codec
• Error logs indicating failures in the BitstreamWriter::write_bits() function or bitstream processing modules

Detection Strategies

Organizations can implement the following detection strategies for CVE-2025-63095:

1. Software Composition Analysis (SCA): Scan your codebase and dependencies to identify if hello-video-codec v0.1.0 is in use
2. Application Monitoring: Monitor applications using the video codec library for unexpected crashes or resource exhaustion patterns
3. Input Validation Logging: Enable detailed logging around media file processing to identify potentially malicious input attempts
4. Runtime Protection: Deploy endpoint detection and response (EDR) solutions like SentinelOne that can detect and prevent exploitation attempts at runtime

SentinelOne Singularity Platform provides behavioral AI that can detect anomalous application behavior indicative of DoS exploitation attempts, offering protection even against zero-day variants.

Monitoring Recommendations

Implement continuous monitoring for applications utilizing the hello-video-codec library:

• Monitor process stability and crash patterns for media processing applications
• Track memory and CPU utilization for abnormal spikes during video processing operations
• Implement alerting for repeated failures in bitstream processing functions
• Review application logs for patterns consistent with malformed input processing attempts

How to Mitigate CVE-2025-63095

Immediate Actions Required

• Audit your software inventory to identify applications using Tempus Ex hello-video-codec v0.1.0
• Implement input validation controls upstream of the vulnerable function where possible
• Consider disabling or isolating affected functionality until a patch is available
• Deploy runtime application self-protection (RASP) or EDR solutions to detect exploitation attempts

Patch Information

At the time of this publication, organizations should monitor the official hello-video-codec GitHub repository for security updates and patched releases. Check the repository's releases page and security advisories for the latest version that addresses CVE-2025-63095.

When a patch becomes available, prioritize testing and deployment in affected environments. Ensure all applications and dependencies using the vulnerable library version are updated to the patched release.

Workarounds

If immediate patching is not feasible, implement the following workarounds to reduce risk:

• Implement strict input validation and sanitization before processing media files with the affected library
• Run applications using the vulnerable library in sandboxed or containerized environments to limit the impact of DoS conditions
• Apply rate limiting and resource constraints to processes handling video codec operations
• Consider using alternative video codec libraries until a patched version is available
• Implement process monitoring and automatic restart mechanisms to minimize service disruption

For applications that must continue using the vulnerable version, implement application-level input validation that validates bitstream data before passing it to the write_bits() function, rejecting malformed or suspicious input patterns.