CVE-2025-1991 in Informix Dynamic Server
Summary
by MITRE • 06/28/2025
IBM Informix Dynamic Server 12.10,14.10, and15.0 could allow a remote attacker to cause a denial of service due to an integer underflow when processing packets.
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Analysis
by VulDB Data Team • 08/14/2025
IBM Informix Dynamic Server versions 12.10, 14.10, and 15.0 contain a critical integer underflow vulnerability that can be exploited by remote attackers to trigger a denial of service condition. This vulnerability stems from improper input validation during packet processing operations where the system fails to correctly handle boundary conditions in integer arithmetic operations. The flaw occurs when the server receives specially crafted network packets that contain malformed integer values, causing the application to perform arithmetic operations that result in integer underflow conditions. Such conditions can lead to unexpected behavior including memory corruption, stack corruption, or abrupt application termination, ultimately resulting in service disruption for legitimate users.
The technical implementation of this vulnerability involves the server's packet parsing logic where integer variables representing packet sizes, sequence numbers, or other network protocol fields are not properly validated against negative values or overflow conditions. When these variables underflow, they can cause the program to jump to invalid memory addresses or execute unintended code paths, potentially leading to complete system crash or hang state. The vulnerability is classified under CWE-191 Integer Underflow or Wraparound which is a well-documented weakness in software systems where arithmetic operations produce results that are outside the range of the data type being used. This specific implementation flaw allows an attacker to manipulate network traffic to force the server into an unstable state through carefully constructed packet payloads.
The operational impact of this vulnerability extends beyond simple denial of service as it can potentially provide a foothold for more sophisticated attacks. Remote attackers can leverage this weakness to repeatedly crash the database server, disrupting business operations and potentially causing data loss or corruption in transit. Organizations running these vulnerable versions of IBM Informix Dynamic Server face significant risk as the attack surface includes any network-accessible database server that has not been patched. The vulnerability affects systems where the database server processes incoming network connections from untrusted sources, making it particularly dangerous in production environments. The integer underflow condition can manifest in various ways including application crashes, system hangs, or even potential privilege escalation scenarios depending on the specific implementation details and system configuration.
Mitigation strategies for this vulnerability should include immediate patching of affected systems with the latest IBM security updates, which typically address the integer validation logic in the packet processing components. Organizations should implement network segmentation and access controls to limit exposure of database servers to untrusted networks, utilizing firewall rules and network access control lists to restrict incoming connections. Additionally, monitoring systems should be configured to detect unusual patterns in database server behavior or connection attempts that might indicate exploitation attempts. The implementation of intrusion detection systems can help identify malicious packet patterns targeting this specific vulnerability. Security teams should also consider implementing automated patch management processes to ensure timely deployment of security updates across all affected systems. Organizations may need to temporarily disable certain network services or implement rate limiting to reduce the attack surface while waiting for official patches. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a common vector for compromising availability in database systems.