Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NSummary
CVE-2026-31883 is a medium-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Freerdp Freerdp. Its CVSS base score is 6.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 24th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-31883 is a size_t underflow vulnerability in the IMA-ADPCM and MS-ADPCM audio decoders of FreeRDP, a free implementation of the Remote Desktop Protocol, affecting versions prior to 3.24.0. Located in libfreerdp/codec/dsp.c, the decoders subtract block header sizes (4 or 8 bytes) from a size_t variable without underflow checks. When a server-supplied nBlockAlign value causes size % block_size == 0 with size smaller than the header, the subtraction wraps size to approximately SIZE_MAX, triggering an astronomically long while (size > 0) loop and leading to a heap-buffer-overflow write via the RDPSND audio channel. It is associated with CWEs-122 (heap-based buffer overflow) and CWE-191 (integer underflow).
The vulnerability carries a CVSS v3.1 base score of 6.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N), indicating network accessibility, low attack complexity, no privileges or user interaction required, and unchanged scope with low confidentiality and integrity impacts but no availability impact. Remote unauthenticated attackers can exploit FreeRDP clients by acting as RDP servers and sending crafted audio data over the RDPSND channel, potentially enabling partial information disclosure or modification through the resulting buffer overflow.
FreeRDP addresses the issue in version 3.24.0. The GitHub security advisory GHSA-85x9-4xxp-xhm5 and fixing commit 16df2300e1e3f5a51f68fb1626429e58b531b7c8 detail the patch, which practitioners should apply by upgrading affected clients.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12061
Vulnerability Data
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…
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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(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.4.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.
Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.
Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.
Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development and acceptance can detect heap overflows before release.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.
Change management ensures controlled deployment of fixes for discovered heap-overflow vulnerabilities.