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Vulnerability record · CVE-2026-63633 · published 19 August 2026

CVE-2026-63633: Freerdp heap-based buffer overflow vulnerability

Freerdp · Freerdp

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.28.0, freerdp_dsp_decode_opus in libfreerdp/codec/dsp.c calls Stream_EnsureRemainingCapacity on context->common.buffer even though opus_decode writes decoded PCM into the caller-supplied out stream. A malicious RDP server that negotiates WAVE_FORMAT_OPUS with a client built with WITH_OPUS enabled and WITH_DSP_FFMPEG disabled can make libopus write a large decoded frame beyond the 4096-byte StreamPool_Take destination used by channels/rdpsnd/client/rdpsnd_main.c. This can corrupt the client heap, crash the client, and may permit code execution. This issue is fixed in version 3.28.0.

7.7 CVSS 4.0 High EPSS 0.62% · top 52.5% CWE-122 · Heap-based buffer overflow
7.7CVSS 4.0 base score
0.62%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 1 tagged exploit
24 Sep 2026Last modified by NVD

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.28.0, freerdp_dsp_decode_opus in libfreerdp/codec/dsp.c calls Stream_EnsureRemainingCapacity on context->common.buffer even though opus_decode writes decoded PCM into the caller-supplied out stream. A malicious RDP server that negotiates WAVE_FORMAT_OPUS with a client built with WITH_OPUS enabled and WITH_DSP_FFMPEG disabled can make libopus write a large decoded frame beyond the 4096-byte StreamPool_Take destination used by channels/rdpsnd/client/rdpsnd_main.c. This can corrupt the client heap, crash the client, and may permit code execution. This issue is fixed in version 3.28.0.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/FreeRDP/FreeRDP/commit/0ed1f95d36913581cf31124f94eb5843d4263eae Patch
https://github.com/FreeRDP/FreeRDP/pull/12993 Issue TrackingPatch
https://github.com/FreeRDP/FreeRDP/releases/tag/3.28.0 Release Notes
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-72j9-356v-88xq ExploitMitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-63633), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.