# CVE-2026-22858

## Summary

- **CVE ID:** CVE-2026-22858
- **Severity:** MEDIUM
- **CVSS Score:** 7.4 (CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P)
- **CWE:** CWE-125, CWE-758
- **Published:** Jan 14, 2026
- **Last Modified:** Aug 19, 2026

## Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.20.1, global-buffer-overflow was observed in FreeRDP's Base64 decoding path. The root cause appears to be implementation-defined char signedness: on Arm/AArch64 builds, plain char is treated as unsigned, so the guard c <= 0 can be optimized into a simple c != 0 check. As a result, non-ASCII bytes (e.g., 0x80-0xFF) may bypass the intended range restriction and be used as an index into a global lookup table, causing out-of-bounds access. This vulnerability is fixed in 3.20.1.

## Affected Products

- FreeRDP — FreeRDP (< 3.20.1)

## References

- [CNA](https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmqf-m84q-x896)
- [CNA](https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2026-22858)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2429649)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-22858.json)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4471)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4121)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:3068)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:19033)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:3334)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4433)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4439)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4446)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4440)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4489)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4437)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:4438)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:3975)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:3067)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.62%
- **EPSS Percentile:** 47.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._