CVE-2026-31883: freerdp Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-31883 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in freerdp. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.8% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 13-03-2026
   PublishedVulnerability first disclosed.
2. 16-03-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
• CWE-191Integer Underflow (Wrap or Wraparound)The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.