cbcvebase.
CVE-2026-23530
published 2026-01-19

CVE-2026-23530: FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0,`freerdp_bitmap_decompress_planar` does not validate…

PriorityP259critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.44%
35.4th percentile
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0,`freerdp_bitmap_decompress_planar` does not validate `nSrcWidth`/`nSrcHeight` against `planar->maxWidth`/`maxHeight` before RLE decode. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.

Affected

3 ranges
VendorProductVersion rangeFixed in
debianfreerdp2< freerdp3 3.21.0+dfsg-1 (forky)freerdp3 3.21.0+dfsg-1 (forky)
debianfreerdp3< freerdp3 3.21.0+dfsg-1 (forky)freerdp3 3.21.0+dfsg-1 (forky)
freerdpfreerdp< 3.21.03.21.0

Detection & IOCsextracted from sources · hover to see the quote

  • The vulnerable function is `freerdp_bitmap_decompress_planar` — monitor for crashes or anomalous heap activity in FreeRDP client processes during RDP bitmap decompression, particularly when connecting to untrusted servers.
  • The attack vector is a malicious RDP server sending specially crafted planar bitmap data to a connecting client — detection should focus on client-side crashes (DoS) or unexpected process termination of FreeRDP client binaries after RDP session establishment.
  • Exploitation requires the FreeRDP client to connect to a maliciously-configured server — alert on FreeRDP client connections to non-approved/external RDP endpoints.
  • ·The vulnerability affects FreeRDP versions prior to 3.21.0 only; version 3.21.0 contains the patch. Ensure deployed FreeRDP clients are upgraded to 3.21.0 or later.
  • ·Red Hat Enterprise Linux 6 will not receive a fix for this CVE — deployments on RHEL 6 remain permanently vulnerable.
  • ·Debian bookworm and bullseye packages remain open/unpatched as of the tracker snapshot — verify current patch status before assuming coverage.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv4.07.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/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
osv7.7HIGH
vendor_debian7.7HIGH
vendor_redhat7.7HIGH
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