CVE-2026-22853: FreeRDP has a heap-buffer-overflow in ndr_read_uint8Array

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-01-14 · updated 2026-07-15
Weakness: CWE-787

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.20.1, RDPEAR’s NDR array reader does not perform bounds checking on the on‑wire element count and can write past the heap buffer allocated from hints, causing a heap buffer overflow in ndr_read_uint8Array. This vulnerability is fixed in 3.20.1.

Affected products

FreeRDP: before 3.20.1 — fixed in 3.20.1

How to fix

Upgrade to a fixed version: FreeRDP 3.20.1. Check the vendor advisory for mitigations.

References

https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-47v9-p4gp-w5ch
https://access.redhat.com/errata/RHSA-2026:19033
https://access.redhat.com/errata/RHSA-2026:3068
https://access.redhat.com/errata/RHSA-2026:4121
https://access.redhat.com/security/cve/CVE-2026-22853
https://bugzilla.redhat.com/show_bug.cgi?id=2429647
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-22853.json

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