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Fencer Intel
critical 9.8

CVE-2026-63633 json

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

published 4mo ago modified 16d ago also EUVD-2026-62672 , GHSA-72j9-356v-88xq

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository FreeRDP/FreeRDP. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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.

Patch / fix

  • freerdp freerdp 3.28.0
  • freerdp3 Debian 14 3.28.0+dfsg-1

debian advisories DEBIAN-CVE-2026-63633

  • freerdp3 Ubuntu 24.04 LTS 3.30.0+dfsg-0ubuntu0.24.04.1
  • freerdp3 Ubuntu 26.04 LTS 3.30.0+dfsg-0ubuntu0.26.04.1

ubuntu advisories UBUNTU-CVE-2026-63633

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • freerdp RHEL 10.2 2:3.10.3-12.el10_2.10
  • libwinpr RHEL 10.2 2:3.10.3-12.el10_2.10
  • freerdp-libs RHEL 10.2 2:3.10.3-12.el10_2.10
  • freerdp-server RHEL 10.2 2:3.10.3-12.el10_2.10
  • freerdp enterprise linux eus 10.0 2:3.10.3-3.el10_0.16
  • libwinpr enterprise linux eus 10.0 2:3.10.3-3.el10_0.16
  • freerdp-libs enterprise linux eus 10.0 2:3.10.3-3.el10_0.16
  • freerdp-server enterprise linux eus 10.0 2:3.10.3-3.el10_0.16

red hat advisories RHSA-2026:68706RHSA-2026:61378

  • freerdp openSUSE Tumbleweed 3.30.0-1.1

opensuse advisories openSUSE-SU-2026:11385-1

  • freerdp AlmaLinux 10 2:3.10.3-12.el10_2.10
  • libwinpr AlmaLinux 10 2:3.10.3-12.el10_2.10
  • freerdp-libs AlmaLinux 10 2:3.10.3-12.el10_2.10
  • freerdp-server AlmaLinux 10 2:3.10.3-12.el10_2.10

almalinux advisories ALSA-2026:61378

  • freerdp Rocky Linux 10 2:3.10.3-12.el10_2.10

rocky linux advisories RLSA-2026:61378

Is CVE-2026-63633 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-63633 updated cvss 8.8

freerdp: FreeRDP: Arbitrary code execution via heap buffer overflow in Opus audio decode

  • Red Hat Enterprise Linux AppStream (v. 10) freerdp 3.10.3-12.el10_2.10, libwinpr 3.10.3-12.el10_2.10, freerdp-libs 3.10.3-12.el10_2.10
    fixed: vendor fix “To mitigate this vulnerability, disable audio redirection on client connections by omitting audio parameters (such as `/sound` or `/audio`) in `xfreerdp` to bypass client-side DSP audio decoding.” RHSA-2026:61378
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp 3.10.3-3.el10_0.16, libwinpr 3.10.3-3.el10_0.16, freerdp-libs 3.10.3-3.el10_0.16
    fixed: vendor fix “To mitigate this vulnerability, disable audio redirection on client connections by omitting audio parameters (such as `/sound` or `/audio`) in `xfreerdp` to bypass client-side DSP audio decoding.” RHSA-2026:68706
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-server 3.10.3-12.el10_2.10
    fixed: vendor fix “To mitigate this vulnerability, disable audio redirection on client connections by omitting audio parameters (such as `/sound` or `/audio`) in `xfreerdp` to bypass client-side DSP audio decoding.” RHSA-2026:61378
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-server 3.10.3-3.el10_0.16
    fixed: vendor fix “To mitigate this vulnerability, disable audio redirection on client connections by omitting audio parameters (such as `/sound` or `/audio`) in `xfreerdp` to bypass client-side DSP audio decoding.” RHSA-2026:68706
  • Red Hat Enterprise Linux 6 freerdp, freerdp-libs, freerdp-plugins Red Hat Enterprise Linux 7 freerdp, libwinpr, freerdp-libs, freerdp-plugins Red Hat Enterprise Linux 8 freerdp, libwinpr, freerdp-libs Red Hat Enterprise Linux 9 freerdp, libwinpr, freerdp-libs
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-72j9-356v-88xq referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.7 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
CNA 4.0 7.7 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:X/V:X/RE:X/U:X
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • FreeRDP FreeRDP

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of FreeRDP/FreeRDP published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.