CVE-2025-4478 Overview
A NULL pointer dereference vulnerability has been discovered in FreeRDP as used by Anaconda's remote install feature. When a specially crafted RDP packet is received, the service experiences a segmentation fault, causing a denial of service condition. This vulnerability is particularly significant because it occurs during the pre-boot phase, meaning systems affected by this flaw become completely defunct and require a full reboot to recover functionality.
Critical Impact
Attackers can remotely crash systems during the pre-boot installation phase, disrupting enterprise deployment workflows and requiring manual intervention to recover affected machines.
Affected Products
- FreeRDP (all vulnerable versions)
- Red Hat Enterprise Linux 10.0
- Anaconda installer with remote install feature enabled
Discovery Timeline
- 2025-05-16 - CVE-2025-4478 published to NVD
- 2025-10-29 - Last updated in NVD database
Technical Details for CVE-2025-4478
Vulnerability Analysis
This vulnerability is classified as CWE-476 (NULL Pointer Dereference). The flaw exists in the FreeRDP library's RDP packet processing code, which is utilized by Anaconda's remote installation feature. When the vulnerable code path encounters a malformed RDP packet, it fails to properly validate pointer references before dereferencing them, leading to a segmentation fault.
The denial of service impact is significant because the vulnerability manifests during the pre-boot installation phase. When exploited, the entire installation service crashes and cannot recover without a system reboot. This makes the vulnerability particularly disruptive in automated deployment scenarios where manual intervention would not normally be expected.
Root Cause
The root cause is a missing NULL pointer check in FreeRDP's RDP packet handling routines. When processing certain malformed or specially crafted RDP packets, the code attempts to dereference a pointer that has not been properly initialized or has been set to NULL due to error conditions. The absence of defensive NULL checks before pointer dereferencing allows attackers to trigger a segmentation fault by sending crafted network packets.
Attack Vector
The attack vector is network-based and requires user interaction (such as connecting to a malicious RDP server or accepting a malicious connection). An attacker can exploit this vulnerability by:
- Setting up a malicious RDP endpoint that responds with crafted packets
- Waiting for or enticing a target system using Anaconda's remote install feature to connect
- Sending malformed RDP packets that trigger the NULL pointer dereference
- Causing the target service to crash, rendering the installation process defunct
The vulnerability is exploitable remotely without authentication, though user interaction is required to initiate the connection to the malicious endpoint.
Detection Methods for CVE-2025-4478
Indicators of Compromise
- Unexpected segmentation faults in FreeRDP or Anaconda processes during remote installation
- System crash logs showing SIGSEGV signals originating from FreeRDP library components
- Failed installation attempts that coincide with RDP connection establishment
- Repeated reboot cycles during automated deployment processes
Detection Strategies
- Monitor system logs for segmentation fault events associated with freerdp or anaconda processes
- Implement network intrusion detection rules to identify malformed RDP packets
- Track installation process failures that occur immediately after RDP session initiation
- Deploy endpoint detection to identify unusual RDP traffic patterns during pre-boot operations
Monitoring Recommendations
- Enable verbose logging for Anaconda remote installation processes
- Configure crash dump collection for pre-boot environments where possible
- Monitor network traffic to and from systems during the installation phase
- Establish baseline metrics for installation success rates to detect anomalous failure patterns
How to Mitigate CVE-2025-4478
Immediate Actions Required
- Apply the latest FreeRDP security updates as referenced in GitHub FreeRDP Pull Request #11573
- Update Red Hat Enterprise Linux systems using the patch from RHSA-2025:9307
- Restrict network access to systems during remote installation phases
- Consider using local installation methods until patches are applied
Patch Information
Red Hat has released security errata RHSA-2025:9307 addressing this vulnerability. The fix is also available upstream via FreeRDP Pull Request #11573. Organizations should prioritize updating FreeRDP packages on systems that utilize Anaconda's remote installation feature. Additional details are available from the Red Hat CVE-2025-4478 advisory.
Workarounds
- Disable the remote install feature in Anaconda if not required for deployment operations
- Isolate systems undergoing remote installation on dedicated network segments
- Use firewall rules to restrict RDP traffic to trusted sources only during installation
- Implement network-level inspection to filter malformed RDP packets before they reach target systems
# Example: Restrict RDP traffic during installation using firewall rules
# Only allow RDP from trusted installation servers
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="10.0.0.0/24" port port="3389" protocol="tcp" accept'
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" port port="3389" protocol="tcp" drop'
firewall-cmd --reload
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
