anyanything/CVE-2026-8461-PoC

GitHubRepository PoCExploit

PoC files

2 files

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GitHub
Analysisdeepseek-v4-pro:cloud ·

Technical assessment

A Python script that generates a malicious AVI file to exploit CVE-2026-8461, an out-of-bounds write in FFmpeg's MagicYUV decoder. The script crafts a video file that, when processed by a vulnerable FFmpeg, triggers a heap overflow to overwrite an AVBuffer struct, hijacking its free function pointer to execute an arbitrary shell command via system().

Backdoor review

No backdoor observed in reviewed code

The repository contains a Python script that generates a malicious AVI file to exploit CVE-2026-8461 in FFmpeg. The script's behavior is consistent with a publicly documented exploit chain: it crafts a MagicYUV video file that triggers an out-of-bounds write to hijack an AVBuffer structure and redirect execution to system(). The code includes no hidden or deceptive functionality beyond the stated exploit generation. The README warns the PoC is AI-generated. No backdoor, trojan, or unrelated harmful behavior was observed.

ClassificationExploit
Model confidence95%
AuthenticationNot required
LanguagesPython
Target softwareFFmpeg
Attack typesRemote Code ExecutionHeap Out-of-Bounds Write
Evidence & reasoningClassification basis · observed behavior · safety review
Technical evidence

Classification basis and observed behavior

Classification basis

The script is explicitly designed to generate a malicious media file that, when processed by a vulnerable FFmpeg, triggers a heap out-of-bounds write to hijack control flow and execute an arbitrary shell command. This constitutes exploit code, not merely a scanner or writeup.

exploit_cve_2026_8461.py:3-6exploit_cve_2026_8461.py:9-11exploit_cve_2026_8461.py:35

Requirements

  • ASLR must be disabled on the target system.exploit_cve_2026_8461.py:19
  • The target must use glibc malloc (jemalloc breaks the heap layout).exploit_cve_2026_8461.py:20
  • The attacker must calibrate heap offsets for the specific target FFmpeg build and file path length.exploit_cve_2026_8461.py:21
  • The target must be running a vulnerable version of FFmpeg (before 8.1.2).exploit_cve_2026_8461.py:22

Observed behavior

  • Generates a MagicYUV-encoded AVI file with a crafted odd slice_height that causes an out-of-bounds write in the decoder.exploit_cve_2026_8461.py:54exploit_cve_2026_8461.py:383
  • Uses left-prediction encoding to place a crafted payload on the heap that overwrites an adjacent AVBuffer struct.exploit_cve_2026_8461.py:13-16exploit_cve_2026_8461.py:92-103
  • Overwrites the AVBuffer.free function pointer with the address of system() and sets AVBuffer.opaque to point to an attacker-controlled command string on the heap.exploit_cve_2026_8461.py:225-231
  • When FFmpeg processes the generated AVI file, the corrupted AVBuffer is freed, causing system() to be called with the attacker's command, achieving remote code execution.exploit_cve_2026_8461.py:5-6exploit_cve_2026_8461.py:700
Safety-review evidence

Behaviors behind the backdoor verdict

Observables

Exploit Chain
OOB Write → AVBuffer.free hijack → system()The script's documented purpose is to generate an AVI file that exploits CVE-2026-8461 for remote code execution. This is the normal behavior of a PoC exploit generator.exploit_cve_2026_8461.py:5-6
Shell Command Execution
system() call with attacker-controlled commandThe exploit payload overwrites AVBuffer.free with the address of system() and sets AVBuffer.opaque to a heap address containing a shell command. This is the intended RCE mechanism of the exploit, not a backdoor in the generator script itself.exploit_cve_2026_8461.py:225-231
Calibration Requirement
ASLR disabled, glibc malloc, calibrated heap offsetsThe script requires specific target conditions (ASLR disabled, known heap layout) to achieve RCE. This is typical for memory corruption exploits and does not indicate a backdoor.exploit_cve_2026_8461.py:18-22
Review boundaries

What the analysis did not establish

  • The evidence consists of the complete source code of the exploit generator and its README. No binary files were present. The analysis is based solely on static review of the provided text; the code was not executed.
  • The exploit requires specific, non-default target conditions (ASLR disabled, glibc malloc, calibrated heap offsets) and is not a universal, turnkey exploit.
  • Only the two text files (README.md and exploit_cve_2026_8461.py) were reviewed. No binary files were present in the evidence.
  • The review does not assess the safety or correctness of the generated AVI file; it only evaluates the PoC generator script for backdoor behavior.
Model interpretation

This review is limited to the supplied PoC code and context. It does not assert that the code works or is safe to execute.

Linked vulnerabilities

1