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Vulnerability · Published Aug 19, 2026 · Assigned by GitHub_M

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

High 7.7

In plain English

A high-severity heap buffer overflow in FreeRDP from FreeRDP. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.7High
Exploit odds (30 days)0.6%top 50.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10freerdp2:3.10.3-12.el10_2.10ALSA-2026:61378
AlmaLinux:10freerdp-devel2:3.10.3-12.el10_2.10ALSA-2026:61378
AlmaLinux:10freerdp-libs2:3.10.3-12.el10_2.10ALSA-2026:61378
AlmaLinux:10freerdp-server2:3.10.3-12.el10_2.10ALSA-2026:61378
AlmaLinux:10libwinpr2:3.10.3-12.el10_2.10ALSA-2026:61378
AlmaLinux:10libwinpr-devel2:3.10.3-12.el10_2.10ALSA-2026:61378
Debian:12freerdp2no fix listedDEBIAN-CVE-2026-63633
Debian:13freerdp3no fix listedDEBIAN-CVE-2026-63633
Debian:14freerdp33.28.0+dfsg-1DEBIAN-CVE-2026-63633
Rocky Linux:10freerdp2:3.10.3-12.el10_2.10RLSA-2026:61378
Ubuntu:22.04:LTSfreerdp2no fix listedUBUNTU-CVE-2026-63633
Ubuntu:24.04:LTSfreerdp33.30.0+dfsg-0ubuntu0.24.04.1UBUNTU-CVE-2026-63633
Ubuntu:26.04:LTSfreerdp33.30.0+dfsg-0ubuntu0.26.04.1UBUNTU-CVE-2026-63633

Affected products (as reported)

VendorProductVersions
FreeRDP FreeRDP < 3.28.0

Weakness: CWE-122 · Vector: 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

References