Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HSummary
CVE-2026-33986 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Freerdp Freerdp. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
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-2026-33986 affects FreeRDP, a free implementation of the Remote Desktop Protocol, in versions prior to 3.24.2. The vulnerability is in the yuv_ensure_buffer() function within libfreerdp/codec/h264.c, where the h264->width and h264->height fields are updated before a reallocation loop involving winpr_aligned_recalloc() calls. If any reallocation fails, the function returns FALSE while leaving the dimensions inflated, potentially leading to memory corruption. This issue maps to CWE-122 (Heap-based Buffer Overflow) and CWE-131 (Incorrect Calculation of Buffer Size), with a CVSS v3.1 base score of 7.5 (AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H), published on 2026-03-30.
The vulnerability can be exploited remotely over the network by an unauthenticated attacker requiring high attack complexity and user interaction. A victim must connect via FreeRDP to a malicious RDP server that triggers the faulty H.264 decoding path, causing the inflated dimensions to mismanage buffers upon reallocation failure and enabling arbitrary code execution or denial of service with high impacts to confidentiality, integrity, and availability.
FreeRDP version 3.24.2 patches this issue. Mitigation details are provided in the GitHub commit at https://github.com/FreeRDP/FreeRDP/commit/f6e43e208958140074ae9bb93cd0c9045a371c77 and the security advisory at https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-h6qw-wxvm-hf97.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-17233
Vulnerability Data
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, in yuv_ensure_buffer() in libfreerdp/codec/h264.c, h264->width and h264->height are updated before the reallocation loop. If any winpr_aligned_recalloc() call fails, the function returns FALSE but width/height are already…
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inflated. This issue has been patched in version 3.24.2.
- 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.
Flaw-remediation processes that include vulnerability scanning or static analysis will surface buffer-size errors.
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.
Secure coding standards directly require correct buffer-size calculations.
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.
Change management ensures controlled deployment of fixes for discovered heap-overflow vulnerabilities.