CVE-2026-31883CWE-122CWE-191

FreeRDP has a `size_t` underflow in ADPCM decoder leads to heap-buffer-overflow write

Medium · published March 13, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
24.9
In the wild
Unconfirmed
What it is

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, a size_t underflow in the IMA-ADPCM and MS-ADPCM audio decoders leads to heap-buffer-overflow write via the RDPSND audio channel. In libfreerdp/codec/dsp.c, the IMA-ADPCM and MS-ADPCM decoders subtract block header sizes from a size_t variable without checking for underflow. When nBlockAlign (received from the server) is set such that size % block_size == 0 triggers the header parsing at a point where size is smaller than the header (4 or 8 bytes), the subtraction wraps size to ~SIZE_MAX. The while (size > 0) loop then continues for an astronomical number of iterations. This vulnerability is fixed in 3.24.0.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00330 · 24.9th percentile
Weaknesses
CWE-122 · Heap-based Buffer Overflow; CWE-191 · Integer Underflow (Wrap or Wraparound)
Published
2026-03-13T17:35Z
EPSS history
Timeline
  • 13 MAR 17:35Z
    FreeRDP has a `size_t` underflow in ADPCM decoder leads to heap-buffer-overflow write
    cvelistv5