External risk intelligence

FFmpeg RIST Protocol Heap Overflow

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-75143

FFmpeg is typically a library embedded in larger apps. While the RIST protocol can be used in network streaming, this vulnerability requires the library to process untrusted input via the async:rist:// URL scheme. Exposure depends entirely on whether a host application implements this specific, non-default protocol scheme and exposes it to untrusted network traffic.

Buffer Overflow

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in FFmpeg's RIST protocol reader could allow a remote attacker to cause a buffer overflow. This issue is reachable via the `async:rist://` URL scheme, potentially impacting applications that process untrusted network streams using this specific protocol. The main concern is confirming relevance and exposure to the RIST protocol.

A flaw in FFmpeg could enable remote attacks.
Matters if your apps use the RIST protocol.
Confirm RIST protocol usage and exposure.

Attack Path

How an attacker could exploit the issue

A remote attacker can send specially crafted network packets to a vulnerable FFmpeg instance to trigger a heap buffer overflow. This occurs when the RIST protocol reader processes a packet with a payload larger than the buffer allocated for it, leading to a crash or potential code execution.

No privileges or user interaction needed.
RIST sender sends oversized packet.
Memory corruption, denial of service.

Live Threat

Current exploitation, exposure, and threat context

When FFmpeg's RIST protocol reader processes specially crafted network packets, it could lead to a heap buffer overflow. This occurs when the RIST reader incorrectly handles packet sizes, potentially overwriting adjacent memory when processing data through the `async:rist://` URL scheme.

System memory corruption.
Network data overflow.
Unspecified service disruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

Application owners and infrastructure teams are most likely responsible for addressing this heap buffer overflow in FFmpeg's RIST protocol reader. The first practical step is to identify all systems running FFmpeg, determine if they process untrusted input via the `async:rist://` URL scheme, and assess their business criticality. Once the scope and impact are understood, the accountable owner can plan remediation, which may involve coordinating with vendors or applying patches during scheduled maintenance windows.

Identify FFmpeg deployments processing RIST input.
Verify RIST protocol reachability and criticality.
Plan remediation or vendor engagement.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is FFmpeg and why is it used?

FFmpeg is a widely used software suite and library for processing multimedia data, including video, audio, and streaming protocols. Developers integrate it into applications to perform tasks like converting file formats, recording streams, and streaming media over networks. Because of its versatility, it is frequently embedded as a backend engine within media players, streaming platforms, and broadcast software to handle complex data stream tasks.

What is the heap buffer overflow in CVE-2026-75143?

This is a memory corruption vulnerability classified as CWE-122. It occurs because the FFmpeg RIST protocol reader fails to check if an incoming data packet fits into the allocated memory buffer. When a sender transmits a packet larger than the designated space, the excess data spills into adjacent memory, which can lead to application crashes or potentially allow an attacker to manipulate the program's execution.

How can an attacker trigger this vulnerability?

An attacker can trigger this by sending a specially crafted, oversized packet to an application that processes data using the async:rist:// URL scheme. It is important to note that if your application uses FFmpeg but does not explicitly implement or accept input through this specific async RIST protocol scheme, it is not affected by this particular defect.

Is my system at risk for CVE-2026-75143?

Risk depends on whether your software consumes untrusted network streams via the async:rist:// scheme. According to Halo Surface Signal, this is not a default configuration for every FFmpeg implementation. You are primarily at risk if you are running custom or third-party applications that have explicitly enabled this specific protocol path to ingest live, potentially untrusted network traffic.

What should I do to address this FFmpeg issue?

Start by identifying all software instances in your environment that rely on FFmpeg. Narrow your search by checking if any of these applications are configured to process input using the async:rist:// URL scheme. If you find such instances, verify if the input source is untrusted and coordinate with your software vendors or internal developers to update to a patched version of the library during your next maintenance cycle.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.