Junglewise Threat Intelligence

CVE-2026-22853: FreeRDP heap buffer overflow in RDPEAR NDR array reader

CVE-2026-22853 · Severity: critical · CVSS 9.8 · Published 2026-01-14

Technologies: Red Hat Enterprise Linux AppStream, Red Hat Enterprise Linux 6, FreeRDP. Vendors: Red Hat, FreeRDP.

Executive brief

FreeRDP is an open-source tool used to connect to remote computers via the Remote Desktop Protocol (RDP). A security flaw in how the software handles certain data packets could allow a malicious server to crash the client application or potentially execute unauthorized code on the user's machine. This could lead to a full system compromise or the theft of sensitive data from the user's session.

Technical details

A heap-based buffer overflow exists in FreeRDP's RDPEAR (Remote Desktop Protocol Enhanced Authentication and RestrictedAdmin) component within the NDR (Network Data Representation) array reader. The function 'ndr_read_pointedMessageEx' allocates a buffer based on 'hints->count', but the subsequent call to 'ndr_read_uconformant_array' reads an element count directly from the network stream without verifying it against the allocated size. An attacker-controlled 'count' larger than the 'hints' value results in an out-of-bounds write during the uint8 array reading loop. This vulnerability can be triggered by a malicious RDP server or a man-in-the-middle attacker to achieve remote code execution or a denial-of-service on the client. The issue is resolved in version 3.20.1.

Affected products

  • FreeRDP FreeRDP < 3.20.1
  • Red Hat Red Hat Enterprise Linux AppStream 10.0, 10.1, 10.2
  • Red Hat Red Hat Enterprise Linux 6 6

Timeline

  • 2026-01-14: advisory: GitHub Security Advisory GHSA-47v9-p4gp-w5ch published
  • 2026-01-14: patched: FreeRDP version 3.20.1 released
  • 2026-01-14: disclosed: CVE-2026-22853 published
  • 2026-05-19: patched: Red Hat released security updates for RHEL 10

References

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