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CVE-2026-63633— FreeRDP: Heap buffer overflow in Opus audio decode (`freerdp_dsp_decode_opus` resizes the wrong stream) — server→client

Quick assessment

Affected
FreeRDP FreeRDP
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FreeRDP是FreeRDP组织开源的一款远程桌面协议(RDP)的实现。 FreeRDP 3.28.0之前版本存在缓冲区错误漏洞，该漏洞源于freerdp_dsp_decode_opus函数在处理Opus音频解码时存在缓冲区错误，可能导致堆破坏、客户端崩溃，甚至执行任意代码。

CVSS 7.7 · High EPSS 0.46% · P39

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProduct Version RangeStatus
FreeRDP FreeRDP < 3.28.0 affected
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I. Basic Information for CVE-2026-63633

Vulnerability Information
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Vulnerability Title
FreeRDP: Heap buffer overflow in Opus audio decode (`freerdp_dsp_decode_opus` resizes the wrong stream) — server→client
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
FreeRDP 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FreeRDP是FreeRDP组织开源的一款远程桌面协议(RDP)的实现。 FreeRDP 3.28.0之前版本存在缓冲区错误漏洞，该漏洞源于freerdp_dsp_decode_opus函数在处理Opus音频解码时存在缓冲区错误，可能导致堆破坏、客户端崩溃，甚至执行任意代码。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeRDP FreeRDP < 3.28.0 -

II. Public POCs for CVE-2026-63633

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8219 chars
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III. Intelligence Information for CVE-2026-63633

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Patches & Fixes for CVE-2026-63633 (3)

Vendor Advisories for CVE-2026-63633 (1)

Same Patch Batch · FreeRDP · 2026-08-19 · 9 CVEs total

CVE-2026-55191 8.7 HIGH FreeRDP: Heap-buffer-overflow write in AVC444 YUV buffer allocation
CVE-2026-55194 8.7 HIGH FreeRDPHeap-buffer-overflow write in TS Gateway RPC RESPONSE reassembly due to alloc_hint
CVE-2026-55193 8.7 HIGH FreeRDP: Heap-buffer-overflow write in TS Gateway RPC fragment receive due to uncapped bin
CVE-2026-55192 7.2 HIGH FreeRDP: Out-of-bounds read in H.264 YUV-to-RGB conversion due to decoder/surface dimensio
CVE-2026-63652 7.1 HIGH FreeRDP: Double-free of `client_formats` in the rdpsnd server channel on a malformed Clien
CVE-2026-63117 6.5 MEDIUM FreeRDP: Denial of service through ADPCM frame size calculation
CVE-2026-55648 6.1 MEDIUM FreeRDP: Integer Overflow in `freerdp_image_copy_from_icon_data` Bypasses Bounds Check
CVE-2026-55564 5.4 MEDIUM FreeRDP: Out-of-bounds read in glyph_cache_get via crafted glyph fragments

IV. Related Vulnerabilities

Same product: FreeRDP
Same vendor: FreeRDP
Same weakness: CWE-122

V. Comments for CVE-2026-63633

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