CVE-2023-39355 – This CVE describes a use-after-free vulnerabili... (How to Fix)

📋 TL;DR

This CVE describes a use-after-free vulnerability in FreeRDP's processing of RDPGFX_CMDID_RESETGRAPHICS packets. When context->maxPlaneSize is 0, the planesBuffer is freed but the pointer isn't updated, creating an exploit vector. This affects FreeRDP 3.x beta releases before beta3 and could lead to crashes or potential remote code execution.

💻 Affected Systems

Products:

FreeRDP

Versions: FreeRDP 3.x releases before version 3.0.0-beta3

Operating Systems: Linux, Windows, macOS, BSD

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects the 3.x beta branch. Stable 2.x releases are not affected.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to full system compromise of the FreeRDP client or server.

🟠

Likely Case

Application crash (denial of service) when processing malicious RDP packets.

🟢

If Mitigated

No impact if patched or if exploit attempts are blocked by network controls.

🌐 Internet-Facing: MEDIUM - FreeRDP servers exposed to internet could be targeted, but exploitation requires specific conditions.

🏢 Internal Only: LOW - Internal RDP connections are typically trusted, reducing attack surface.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires sending specially crafted RDPGFX packets to trigger the use-after-free condition.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 3.0.0-beta3 and later

Vendor Advisory: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-hvwj-vmg6-2f5h

Restart Required: Yes

Instructions:

1. Check current FreeRDP version: freerdp --version
2. If version is < 3.0.0-beta3, upgrade using package manager or compile from source
3. For Debian/Ubuntu: apt update && apt upgrade freerdp2
4. For RHEL/CentOS: yum update freerdp
5. Restart any FreeRDP services or applications

🔧 Temporary Workarounds

No known workarounds

all

The vendor advisory states there are no known workarounds for this vulnerability.

🧯 If You Can't Patch

Restrict network access to FreeRDP services using firewalls to only trusted sources.
Monitor for crash logs and unusual RDP connection attempts as indicators of exploitation.

🔍 How to Verify

Check if Vulnerable:

Run: freerdp --version | grep -E '^3\.' && echo "Check if version is < 3.0.0-beta3"

Check Version:

freerdp --version

Verify Fix Applied:

Confirm version is 3.0.0-beta3 or higher: freerdp --version

📡 Detection & Monitoring

Log Indicators:

FreeRDP crash logs
Segmentation fault errors in system logs
Unexpected termination of FreeRDP processes

Network Indicators:

Unusual RDPGFX packet patterns
Multiple RDP connection attempts from single source

SIEM Query:

source="*freerdp*" AND ("segmentation fault" OR "crash" OR "SIGSEGV")

📊 Metadata

CVE ID: CVE-2023-39355

CVSS v3 Score: 7.0 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

CWE: CWE-416

Published: August 31, 2023

Last Updated: November 21, 2024

🔗 References

https://github.com/FreeRDP/FreeRDP/commit/d6f9d33a7db0b346195b6a15b5b99944ba41beee Patch
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-hvwj-vmg6-2f5h Exploit,Vendor Advisory
https://lists.debian.org/debian-lts-announce/2023/10/msg00008.html Mailing List,Third Party Advisory
https://security.gentoo.org/glsa/202401-16
https://github.com/FreeRDP/FreeRDP/commit/d6f9d33a7db0b346195b6a15b5b99944ba41beee Patch
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-hvwj-vmg6-2f5h Exploit,Vendor Advisory
https://lists.debian.org/debian-lts-announce/2023/10/msg00008.html Mailing List,Third Party Advisory
https://security.gentoo.org/glsa/202401-16

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2023-39355, you might also want to check these: