CVE-2026-0710: SIPp Denial of Service (DoS) Vulnerability

CVE-2026-0710 Overview

A NULL pointer dereference vulnerability has been discovered in SIPp, an open-source test tool and traffic generator for the SIP protocol. A remote attacker could exploit this flaw by sending specially crafted Session Initiation Protocol (SIP) messages during an active call. This vulnerability can cause the application to crash, leading to a denial of service. Under specific conditions, it may also allow an attacker to execute unauthorized code, compromising the system's integrity and availability.

Critical Impact

This vulnerability allows remote attackers to cause application crashes through malformed SIP messages, potentially disrupting critical VoIP testing infrastructure and, in certain scenarios, achieving code execution.

Affected Products

• SIPp (all versions prior to patch)
• Systems using SIPp for SIP protocol testing
• VoIP testing infrastructure utilizing SIPp

Discovery Timeline

• 2026-01-23 - CVE-2026-0710 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-0710

Vulnerability Analysis

This vulnerability is classified as CWE-476 (NULL Pointer Dereference), which occurs when an application dereferences a pointer that is expected to be valid but is NULL. In the context of SIPp, the flaw manifests during the processing of specially crafted SIP messages while an active call is in progress.

The NULL pointer dereference condition can be triggered remotely when malicious SIP messages are sent to a SIPp instance. When the application attempts to access memory through the NULL pointer, it results in undefined behavior—most commonly causing an immediate application crash. However, depending on the system architecture, memory layout, and exploitation techniques, attackers may potentially leverage this condition to achieve code execution.

The vulnerability requires local access to exploit according to the attack vector, suggesting that while the malicious SIP messages can be sent remotely, the actual exploitation may depend on local system conditions or require local access for full impact.

Root Cause

The root cause of this vulnerability lies in insufficient validation of SIP message contents before pointer dereferencing operations. When SIPp receives and processes SIP protocol messages during active call scenarios, certain message fields or states may result in NULL pointer assignments. The application fails to verify that these pointers reference valid memory locations before attempting to dereference them, leading to the NULL pointer dereference condition.

Attack Vector

The attack vector involves sending specially crafted SIP messages to a target SIPp instance during an active call session. The attacker must craft malformed or unexpected SIP message content that triggers the code path leading to the NULL pointer dereference.

The exploitation scenario typically involves:

1. Identifying a target system running SIPp with active call sessions
2. Crafting malicious SIP messages designed to trigger the vulnerable code path
3. Sending the crafted messages to the target during call processing
4. Causing the application to crash (DoS) or potentially executing unauthorized code

Technical details regarding the specific exploitation mechanism can be found in the Red Hat CVE-2026-0710 Advisory and Red Hat Bug Report #2427788.

Detection Methods for CVE-2026-0710

Indicators of Compromise

• Unexpected SIPp process crashes or restarts during active call testing
• Anomalous SIP message patterns in network traffic logs
• Core dump files indicating NULL pointer access violations in SIPp processes
• Increased frequency of SIP-related error messages in system logs

Detection Strategies

• Monitor SIPp process stability and implement alerting for unexpected terminations
• Deploy network intrusion detection rules to identify malformed SIP message patterns
• Implement SIP-aware application firewalls to filter potentially malicious protocol traffic
• Analyze crash dumps for indicators of NULL pointer dereference exploitation attempts

Monitoring Recommendations

• Enable verbose logging on SIPp instances to capture detailed SIP message processing events
• Configure process monitoring to detect and alert on SIPp crash events
• Implement network traffic analysis for SIP protocol anomalies
• Review system logs regularly for signs of exploitation attempts or crash patterns

How to Mitigate CVE-2026-0710

Immediate Actions Required

• Limit network access to SIPp instances to trusted sources only
• Implement network segmentation to isolate SIP testing infrastructure
• Configure firewall rules to restrict SIP traffic to authorized endpoints
• Consider temporarily disabling SIPp services if not critically needed until patches are applied

Patch Information

Organizations should monitor vendor advisories for official patch releases. Refer to the Red Hat CVE-2026-0710 Advisory for the latest patch information and security guidance. Additionally, track updates via Red Hat Bug Report #2427788 for detailed remediation steps.

Workarounds

• Restrict SIPp network access using firewall rules to allow only trusted IP addresses
• Deploy SIPp instances in isolated network segments with limited external connectivity
• Implement SIP-aware intrusion prevention systems to filter malicious messages
• Use process monitoring tools to automatically restart crashed SIPp instances while maintaining service availability

# Example: Restrict SIPp access using iptables
# Allow SIP traffic only from trusted testing networks
iptables -A INPUT -p udp --dport 5060 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 5060 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p udp --dport 5060 -j DROP
iptables -A INPUT -p tcp --dport 5060 -j DROP