High [CVE-2026-55192] Out-of-bounds read leads to memory disclosure or client crash
This high-severity Red Hat Linux advisory covers CVE-2026-55192 affecting Red Hat Enterprise Linux 7 Extended Lifecycle Support, Red Hat Enterprise Linux 10, Red Hat package: freerdp.
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Summary
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP H.264 decoder backends can return YUV planes sized from the bitstream without comparing the decoded width and height to the RDPGFX surface dimensions used to validate region rectangles.
A malicious RDP server can provide an AVC420 or AVC444 bitstream whose decoded frame is smaller than the negotiated surface, causing yuv420_context_decode and the YUV-to-RGB conversion paths to read beyond the decoder-owned planes in libfreerdp/codec/h264.c and the selected H.264 backend. This can disclose client memory or crash the client.
This issue is fixed in version 3.27.0. A flaw was found in FreeRDP.
When handling AVC420 or AVC444 bitstreams, decoder backends fail to validate frame dimensions against negotiated RDPGFX surface boundaries. Red Hat severity: Important — CVSS 8.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H).
Weakness: CWE-125. Affected Red Hat products: Red Hat Enterprise Linux 7 Extended Lifecycle Support; Red Hat Enterprise Linux 10.
Red Hat lists Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9 as not affected. Red Hat fixing advisory: RHSA-2026:68707.
Affected products named by the advisory: Red Hat package: freerdp.
- < 3.27.0
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
- 3.27.0
- freerdp-0:2.1.1-5.el7_9.12
- RHSA-2026:68707
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
Mitigation checklist
- To mitigate this vulnerability, disable H.264 graphics acceleration in client connection parameters (e.g., omitting `/gfx:avc420` or `/gfx:avc444` in `xfreerdp`) to force legacy RemoteFX or standard software bitmap rendering.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
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