CVE-2026-125195: FFmpeg through 9.0.2 Uninitialized Memory Disclosure via ADPCM_MS Trellis Encoding

Q: Which deployments are exposed to this issue?

Deployments that encode untrusted or attacker-submitted audio as mono ADPCM_MS with trellis enabled are exposed. The disclosed data is returned in the encoded output packets, so the attacker must be able to receive the resulting encoded audio.

Q: What conditions are required for exploitation?

An attacker needs to cause the service to encode audio using the mono ADPCM_MS encoder configuration with trellis enabled. The supplied severity vector also indicates local attack-vector conditions, high attack complexity, no privileges required, and user interaction required.

Q: What can be done if an update cannot be applied immediately?

Avoid or disable trellis encoding for mono ADPCM_MS audio, or avoid producing mono ADPCM_MS output for untrusted audio submissions. Do not return affected encoded output to untrusted requesters.

Q: How can I determine whether a workflow is affected?

Review encoding jobs and service configurations for use of FFmpeg's ADPCM_MS encoder in mono mode with trellis enabled. Test outputs from that path for unexpected data in roughly half of each encoded block, which may indicate stale heap bytes being emitted.

Published Nov 9, 2026

Updated

FFmpeg through 9.0.2 contains an uninitialized memory disclosure vulnerability in adpcmencodeframe() in libavcodec/adpcmenc.c that leaks heap bytes when encoding mono ADPCMMS audio with trellis enabled. Attackers submitting audio to a service using this encoding receive output packets where about half of each block contains stale heap memory from the encoding process.

Affected Software

1 affected component

FFmpeg FFmpeg<=9.0.2

Event History

Nov 9, 2026

CVE Published

via MITRE·07:11 PM

Data Sourced

via MITRE·07:11 PM

DescriptionSeverityWeakness

Data Sourced

via NVD·07:16 PM

DescriptionSeverityWeakness

Frequently Asked Questions

Which deployments are exposed to this issue?

Deployments that encode untrusted or attacker-submitted audio as mono ADPCM_MS with trellis enabled are exposed. The disclosed data is returned in the encoded output packets, so the attacker must be able to receive the resulting encoded audio.

What conditions are required for exploitation?

An attacker needs to cause the service to encode audio using the mono ADPCM_MS encoder configuration with trellis enabled. The supplied severity vector also indicates local attack-vector conditions, high attack complexity, no privileges required, and user interaction required.

What can be done if an update cannot be applied immediately?

Avoid or disable trellis encoding for mono ADPCM_MS audio, or avoid producing mono ADPCM_MS output for untrusted audio submissions. Do not return affected encoded output to untrusted requesters.

How can I determine whether a workflow is affected?

Review encoding jobs and service configurations for use of FFmpeg's ADPCM_MS encoder in mono mode with trellis enabled. Test outputs from that path for unexpected data in roughly half of each encoded block, which may indicate stale heap bytes being emitted.

CVE-2026-125195: FFmpeg through 9.0.2 Uninitialized Memory Disclosure via ADPCM_MS Trellis Encoding

Affected Software

Event History

Frequently Asked Questions

Which deployments are exposed to this issue?

What conditions are required for exploitation?

What can be done if an update cannot be applied immediately?

How can I determine whether a workflow is affected?

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Frequently Asked Questions

Which deployments are exposed to this issue?

What conditions are required for exploitation?

What can be done if an update cannot be applied immediately?

How can I determine whether a workflow is affected?