CVE-2026-63633Public exploitNetwork attack vector

Client heap corruption via wrong stream resize

Published Aug 19, 2026 · Updated Aug 21, 2026

Heap buffer overflow in FreeRDP before 3.28.0 allows remote attackers to crash clients and possibly execute code via crafted Opus audio PDUs. In libfreerdp/codec/dsp.c, freerdp_dsp_decode_opus checks capacity on context->common.buffer, but opus_decode writes decoded PCM into the caller-supplied out stream, so the 4096-byte rdpsnd buffer can be overrun by a large decoded frame. Exposure requires a client build with WITH_OPUS enabled and WITH_DSP_FFMPEG disabled; a malicious or man-in-the-middle RDP server that negotiates WAVE_FORMAT_OPUS can trigger heap corruption after connection with audio redirection active.

CVSS severity7.7
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in FreeRDP before 3.28.0 allows remote attackers to crash clients and possibly execute code via crafted Opus audio PDUs. In libfreerdp/codec/dsp.c, freerdp_dsp_decode_opus checks capacity on context->common.buffer, but opus_decode writes decoded PCM into the caller-supplied out stream, so the 4096-byte rdpsnd buffer can be overrun by a large decoded frame. Exposure requires a client build with WITH_OPUS enabled and WITH_DSP_FFMPEG disabled; a malicious or man-in-the-middle RDP server that negotiates WAVE_FORMAT_OPUS can trigger heap corruption after connection with audio redirection active.

The record

CVE
CVE-2026-63633
Published
Aug 19, 2026
Updated
Aug 21, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-122, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 3.28.0

Published CVSS scores

7.7CVE.org CNACVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1203Exploitation for Client Execution

Public exploit references

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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