Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HSummary
CVE-2026-33984 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 33th 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-2026-33984 is a heap buffer overflow vulnerability in FreeRDP, a free implementation of the Remote Desktop Protocol (RDP). The issue affects versions prior to 3.24.2 and resides in the resize_vbar_entry() function within libfreerdp/codec/clear.c. Specifically, vBarEntry->size is updated to vBarEntry->count before the winpr_aligned_recalloc() call; if the reallocation fails, the size remains inflated while the pixels pointer still references the original smaller buffer. In a follow-up call where count is less than or equal to the inflated size, reallocation is skipped, allowing the caller to write count * bpp bytes of attacker-controlled pixel data into the undersized buffer.
A remote attacker with no privileges can exploit this vulnerability over the network, though it requires high attack complexity and user interaction, such as tricking a user into connecting to a malicious RDP server. Successful exploitation leads to high-impact consequences, including arbitrary code execution, data corruption, or denial of service via the heap buffer overflow, as indicated by the CVSS v3.1 base score of 7.5 (AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H). The vulnerability is associated with CWE-122 (Heap-based Buffer Overflow) and CWE-131 (Incorrect Calculation of Buffer Size).
The vulnerability has been patched in FreeRDP version 3.24.2. Security practitioners should update to this version or later. Additional details are available in the FreeRDP security advisory (GHSA-8469-2xcx-frf6) and the patching commit (dc7fdb165095139be779a4000199bc1706b06ad5) on the project's GitHub repository.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-17229
Vulnerability Data
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, in resize_vbar_entry() in libfreerdp/codec/clear.c, vBarEntry->size is updated to vBarEntry->count before the winpr_aligned_recalloc() call. If realloc fails, size is inflated while pixels still points to the old,…
more
smaller buffer. On a subsequent call where count <= size (the inflated value), realloc is skipped. The caller then writes count * bpp bytes of attacker-controlled pixel data into the undersized buffer, causing a heap buffer overflow. 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
—
—
—
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.