CVE-2025-2176: Zapping-vbi Zvbi RCE Vulnerability

CVE-2025-2176 Overview

A critical integer overflow vulnerability has been discovered in libzvbi, a library for accessing Video Broadcast Information (VBI) services. The vulnerability affects the vbi_capture_sim_load_caption function within the src/io-sim.c file. This integer overflow condition can be triggered remotely, potentially leading to memory corruption, unexpected behavior, or denial of service conditions in applications that utilize the libzvbi library for processing VBI data streams.

Critical Impact

Remote attackers can exploit this integer overflow vulnerability in libzvbi versions up to 0.2.43, potentially causing memory corruption or application crashes in systems processing VBI data.

Affected Products

• zapping-vbi zvbi versions up to 0.2.43
• Applications and systems utilizing the libzvbi library for VBI processing
• Media processing pipelines integrating zvbi components

Discovery Timeline

• 2025-03-11 - CVE-2025-2176 published to NVD
• 2025-10-10 - Last updated in NVD database

Technical Details for CVE-2025-2176

Vulnerability Analysis

This vulnerability is an integer overflow condition (CWE-190) affecting the caption loading functionality within libzvbi. The vulnerable function vbi_capture_sim_load_caption in src/io-sim.c does not properly validate or constrain integer values before performing arithmetic operations. When manipulated input is processed, the integer overflow can cause the application to allocate insufficient memory or incorrectly calculate buffer boundaries, leading to subsequent memory corruption issues.

Integer overflow vulnerabilities are particularly dangerous in C-based libraries like libzvbi because they can bypass security checks and lead to heap or stack corruption. The network attack vector indicates that malicious input can be delivered remotely through crafted VBI data streams or caption files, making this vulnerability exploitable without requiring local access to the target system.

Root Cause

The root cause of CVE-2025-2176 is improper handling of numeric values in the vbi_capture_sim_load_caption function. The function performs arithmetic operations on integer values without adequate bounds checking, allowing an attacker to supply values that cause the integer to wrap around its maximum value. This numeric error (CWE-189) results in unexpected small values being used for memory allocation or array indexing operations, creating exploitable conditions.

Attack Vector

The attack can be initiated remotely by providing maliciously crafted input to applications utilizing the libzvbi library. An attacker could exploit this vulnerability by:

1. Crafting a malicious VBI data stream or caption file with specially calculated integer values
2. Delivering the malicious content to a target system processing VBI data
3. Triggering the vulnerable vbi_capture_sim_load_caption function with the crafted input
4. Causing an integer overflow that leads to memory corruption or application instability

The vulnerability has been publicly disclosed, increasing the urgency for affected systems to apply the available patch.

Detection Methods for CVE-2025-2176

Indicators of Compromise

• Unexpected crashes or segmentation faults in applications using libzvbi for caption processing
• Abnormal memory consumption patterns in VBI-related processes
• Application errors related to vbi_capture_sim_load_caption function calls
• Suspicious VBI data files or streams with unusual size parameters

Detection Strategies

• Monitor application logs for crashes or memory errors in libzvbi-dependent applications
• Implement file integrity monitoring for libzvbi library files to detect unauthorized modifications
• Use memory analysis tools to detect heap or stack corruption in VBI processing workflows
• Deploy intrusion detection signatures to identify malformed VBI data streams

Monitoring Recommendations

• Enable verbose logging for applications processing VBI data to capture potential exploitation attempts
• Implement crash dump analysis for affected applications to identify overflow-related failures
• Monitor network traffic for unusual VBI data patterns that may indicate exploitation attempts

How to Mitigate CVE-2025-2176

Immediate Actions Required

• Upgrade libzvbi to version 0.2.44 or later immediately
• Audit systems for applications dependent on libzvbi and prioritize updates
• Implement network-level filtering for untrusted VBI data sources until patching is complete
• Consider temporarily disabling VBI processing functionality in non-critical applications

Patch Information

The maintainer has addressed this vulnerability in libzvbi version 0.2.44. The fix is available in commit ca1672134b3e2962cd392212c73f44f8f4cb489f. Organizations should upgrade to the patched version as soon as possible.

For additional details, refer to the GitHub Security Advisory GHSA-g7cg-7gw9-v8cf and the GitHub Release v0.2.44.

Workarounds

• Restrict network access to systems processing VBI data until the patch can be applied
• Implement input validation at the application level before passing data to libzvbi functions
• Use application sandboxing or containerization to limit the impact of potential exploitation
• Deploy web application firewalls or content filtering to block suspicious VBI data if applicable

# Upgrade libzvbi to patched version
# For systems using package managers:
# Debian/Ubuntu
sudo apt update && sudo apt install libzvbi-0.2

# From source (if package not available)
git clone https://github.com/zapping-vbi/zvbi.git
cd zvbi
git checkout v0.2.44
./configure && make && sudo make install