Buffer overflow in Freerdp
CVE-2026-63633
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.006 (47.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.002
Affected products
- Freerdp — versions < 3.28.0
Weakness classification (CWE)
References
- github.com/FreeRDP/FreeRDP/commit/0ed1f95d36913581cf31124f94eb5843d4263eae (Patch)
- github.com/FreeRDP/FreeRDP/pull/12993 (Patch, Issue Tracking)
- github.com/FreeRDP/FreeRDP/releases/tag/3.28.0 (Release Notes)
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-72j9-356v-88xq (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-63633?
- CVE-2026-63633 is a critical-severity vulnerability in Freerdp, classified under Heap-based Buffer Overflow. CVSS score: 9.8/10. Published 2026-08-19.
- How severe is CVE-2026-63633?
- Critical severity. CVSS v3 base score is 9.8 out of 10.