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…

PriorityP260critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.53%
44.7th 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

5 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
freerdpfreerdp——
freerdpfreerdp>= 3.21.0 < 3.28.03.28.0

Detection & IOCsextracted from sources · hover to see the quote

  • →Vulnerable function is `freerdp_bitmap_decompress_planar` — monitor for crashes or anomalous heap behavior in FreeRDP client processes invoking this function during RDP bitmap decompression ↗
  • →The incomplete fix (CVE-2026-57158) resides specifically in `planar_decompress_plane_rle_only` in `libfreerdp/codec/planar.c` — instrument or audit this code path for out-of-bounds reads triggered by truncated RDPGFX_CMDID_WIRETOSURFACE_1 planar payloads ↗
  • →Trigger vector is a malicious RDP server sending specially crafted bitmap data to a connecting client — alert on FreeRDP client connections to untrusted/unknown RDP servers, especially where heap crashes follow bitmap decompression ↗
  • →Affected RDP protocol command is RDPGFX_CMDID_WIRETOSURFACE_1 — network-level detection should look for malformed or truncated payloads carrying this GFX command ID over the RDP GFX pipeline ↗
  • ·Exploitation requires the FreeRDP client to actively connect to a malicious server — clients connecting only to trusted servers are not at risk ↗
  • ·FreeRDP versions 3.21.0–3.27.x contain only a partial fix; the GFX pipeline path (`planar_decompress_plane_rle_only`) remains vulnerable to a related one-byte OOB read (CVE-2026-57158) until version 3.28.0 ↗
  • ·Red Hat Enterprise Linux 6 package `freerdp` is marked 'Will not fix' — deployments on RHEL 6 will remain permanently vulnerable ↗
  • ·Debian bookworm and bullseye packages remain open/unpatched as of the tracker snapshot ↗

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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