CVE-2026-63117Network attack vector

Authenticated service interrupt via ADPCM modulo by zero

Published Aug 19, 2026 · Updated Aug 19, 2026

Divide-by-zero in the rdpsnd server channel in FreeRDP before 3.28.0 allows remote authenticated users to crash the audio channel via crafted ADPCM values. In channels/rdpsnd/server/rdpsnd_main.c, rdpsnd_server_select_format accepts client-supplied nBlockAlign and nChannels values that make the ADPCM frame-size variable bs equal zero, then performs out_frames % bs and triggers SIGFPE. Exploitation requires an authenticated RDP client that can negotiate the server-side rdpsnd virtual channel, and the published impact is limited to termination of that channel process rather than code execution or data access.

CVSS severity6.5
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide-by-zero in the rdpsnd server channel in FreeRDP before 3.28.0 allows remote authenticated users to crash the audio channel via crafted ADPCM values. In channels/rdpsnd/server/rdpsnd_main.c, rdpsnd_server_select_format accepts client-supplied nBlockAlign and nChannels values that make the ADPCM frame-size variable bs equal zero, then performs out_frames % bs and triggers SIGFPE. Exploitation requires an authenticated RDP client that can negotiate the server-side rdpsnd virtual channel, and the published impact is limited to termination of that channel process rather than code execution or data access.

The record

CVE
CVE-2026-63117
Published
Aug 19, 2026
Updated
Aug 19, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-369, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.28.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 3.28.0

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero
T1499.004Endpoint Denial of Service Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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