CVE-2025-2263: Sante PACS Server Buffer Overflow Flaw

CVE-2025-2263 Overview

CVE-2025-2263 is a stack-based buffer overflow vulnerability in Sante PACS Server, a medical imaging Picture Archiving and Communication System (PACS) used in healthcare environments. The vulnerability exists in the web server login functionality where the OpenSSL function EVP_DecryptUpdate is called to decrypt user-supplied credentials. A fixed 0x80-byte (128-byte) stack-based buffer is used as the output buffer, which can be overflowed when an unauthenticated remote attacker supplies a long encrypted username or password.

Critical Impact

This vulnerability allows unauthenticated remote attackers to potentially achieve remote code execution on healthcare systems storing sensitive medical imaging data by overflowing a fixed-size stack buffer during the login process.

Affected Products

• Santesoft Sante PACS Server version 4.1.0
• Santesoft Sante PACS Server (earlier versions potentially affected)

Discovery Timeline

• 2025-03-13 - CVE-2025-2263 published to NVD
• 2025-04-03 - Last updated in NVD database

Technical Details for CVE-2025-2263

Vulnerability Analysis

This vulnerability is classified under CWE-121 (Stack-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). The flaw resides in the authentication mechanism of the Sante PACS Server web interface within Sante PACS Server.exe. During the login process, the application decrypts user-supplied credentials using the OpenSSL EVP_DecryptUpdate function. The critical issue is that the application allocates a fixed 0x80-byte (128-byte) buffer on the stack to receive the decrypted output without properly validating the length of the incoming encrypted data.

When an attacker sends an encrypted username or password that decrypts to a value longer than 128 bytes, the EVP_DecryptUpdate function writes beyond the allocated buffer boundaries, corrupting adjacent stack memory. This can overwrite critical stack structures including saved return addresses, potentially allowing an attacker to hijack program execution flow.

Root Cause

The root cause of this vulnerability is improper input validation combined with the use of a fixed-size stack buffer. The application fails to verify that the decrypted credential length will fit within the 0x80-byte output buffer before calling EVP_DecryptUpdate. The OpenSSL decryption function trusts the caller to provide an adequately sized buffer and will write the full decrypted output regardless of buffer size, leading to stack corruption when oversized input is processed.

Attack Vector

This vulnerability is exploitable remotely over the network without authentication. An attacker can craft a malicious HTTP login request containing an overly long encrypted username or password value. When the Sante PACS Server processes this request and attempts to decrypt the credentials, the stack-based buffer overflow occurs. The attack requires no user interaction and can be executed by any network-connected attacker who can reach the web server interface.

The exploitation path involves:

1. Identifying a Sante PACS Server web interface exposed on the network
2. Crafting an encrypted payload that exceeds 128 bytes when decrypted
3. Sending the malicious payload in the username or password field during login
4. Overwriting the return address or other critical stack data to achieve code execution

Due to the lack of verified code examples, readers should refer to the Tenable Security Research Advisory for detailed technical analysis of the vulnerability mechanism.

Detection Methods for CVE-2025-2263

Indicators of Compromise

• Abnormally large HTTP POST requests to the Sante PACS Server login endpoint
• Application crashes or unexpected termination of Sante PACS Server.exe process
• Unusual memory access violations in system event logs related to the PACS server process
• Network traffic containing oversized encrypted credential payloads targeting PACS infrastructure

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests with abnormally large username or password fields targeting PACS servers
• Monitor for process crashes or unexpected restarts of the Sante PACS Server service
• Implement application-level logging to capture and alert on oversized credential submissions
• Use endpoint detection and response (EDR) solutions to identify exploitation attempts through memory corruption detection

Monitoring Recommendations

• Enable detailed logging on all Sante PACS Server instances to capture authentication attempts
• Configure alerts for Sante PACS Server.exe process termination or crash events
• Monitor network perimeter for reconnaissance activity targeting healthcare imaging systems
• Implement network segmentation monitoring to detect lateral movement following potential compromise

How to Mitigate CVE-2025-2263

Immediate Actions Required

• Identify all Sante PACS Server installations within the organization, particularly version 4.1.0
• Restrict network access to Sante PACS Server web interfaces using firewall rules
• Place PACS servers behind VPN or other access control mechanisms to limit exposure
• Implement Web Application Firewall (WAF) rules to block oversized credential payloads

Patch Information

Organizations should contact Santesoft directly for information regarding patched versions of Sante PACS Server that address this vulnerability. Review the Tenable Security Research Advisory for additional details on remediation guidance.

Workarounds

• Isolate Sante PACS Server instances from untrusted networks and the public internet
• Implement network-level access controls to restrict login access to trusted IP ranges only
• Deploy a reverse proxy with input validation to filter oversized credential submissions before they reach the server
• Monitor all authentication attempts and implement rate limiting to detect potential exploitation attempts

# Example firewall configuration to restrict access to PACS web interface
# Allow only trusted medical network subnets
iptables -A INPUT -p tcp --dport 80 -s 10.0.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP