CVE-2026-64830
Received Received - Intake

Heap Buffer Overflow in FFmpeg VobSub Demuxer

Publication date: 2026-07-22

Last updated on: 2026-07-22

Assigner: VulnCheck

Description
FFmpeg versions 2.1 through 8.1.2 contains a heap buffer overflow vulnerability in the VobSub subtitle demuxer that allows attackers to corrupt adjacent heap memory by supplying a malicious .sub/.idx subtitle file declaring more distinct stream IDs than the fixed-size array bounds in libavformat/mpeg.c. Attackers can craft a subtitle file with excessive distinct stream IDs to trigger unbounded writes beyond the vobsub->q[] array boundary via ff_subtitles_queue_insert(), potentially achieving arbitrary code execution in any application using FFmpeg's VobSub demuxer.

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Meta Information

Published
2026-07-22
Last Modified
2026-07-22
Generated
2026-07-22
AI Q&A
2026-07-22
EPSS Evaluated
N/A
NVD
CVE-2026-64830
EUVD
EUVD-2026-47747

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
ffmpeg ffmpeg From 2.1 (inc) to 8.1.2 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.
CWE-122 A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Attack-Flow Graph

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Executive Summary

This is a heap buffer overflow in FFmpeg versions 2.1 through 8.1.2 affecting the VobSub subtitle demuxer. Attackers can exploit it by providing a malicious .sub or .idx file with more distinct stream IDs than the fixed-size array can handle. This causes out-of-bounds writes that corrupt adjacent heap memory, potentially leading to arbitrary code execution in applications using FFmpeg's VobSub demuxer.

Detection Guidance

To detect this vulnerability, inspect FFmpeg versions on your system. Check if any installed version falls within 2.1 through 8.1.2. Use commands like 'ffmpeg -version' or 'dpkg -l | grep ffmpeg' on Linux. Review subtitle files processed by FFmpeg for excessive distinct stream IDs in .sub/.idx files.

Impact Analysis

If you use software that relies on FFmpeg's VobSub demuxer, an attacker could exploit this flaw by tricking you into processing a specially crafted subtitle file. This could lead to memory corruption, crashes, or even arbitrary code execution on your system, potentially allowing the attacker to take control of your device.

Compliance Impact

This vulnerability could lead to arbitrary code execution in applications using FFmpeg's VobSub demuxer, potentially compromising data integrity and confidentiality. For GDPR, this may result in unauthorized access to personal data, violating principles of data protection and security. For HIPAA, it could expose protected health information to unauthorized parties, leading to compliance violations and legal consequences.

Mitigation Strategies

Immediately update FFmpeg to the latest patched version beyond 8.1.2. If updating is not possible, disable the VobSub subtitle demuxer by removing or renaming libavformat/mpeg.c components. Avoid processing untrusted subtitle files until patched.

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