CVE-2007-2437 in Xserver
Summary
by MITRE
The X render (Xrender) extension in X.org X Window System 7.0, 7.1, and 7.2, with Xserver 1.3.0 and earlier, allows remote authenticated users to cause a denial of service (daemon crash) via crafted values to the (1) XRenderCompositeTrapezoids and (2) XRenderAddTraps functions, which trigger a divide-by-zero error.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/08/2025
The vulnerability identified as CVE-2007-2437 affects the X Render extension within the X.org X Window System versions 7.0 through 7.2, specifically when paired with Xserver versions 1.3.0 and earlier. This issue represents a critical flaw in the graphical subsystem that handles rendering operations for X11-based applications, creating a pathway for remote authenticated attackers to disrupt system services through carefully constructed input parameters. The vulnerability manifests in the XRenderCompositeTrapezoids and XRenderAddTraps functions, which are core components of the X Window System's rendering infrastructure responsible for composite operations and trap management respectively.
The technical root cause of this vulnerability lies in insufficient input validation within the X Render extension's implementation. When remote authenticated users submit specially crafted values to the affected functions, the code fails to properly handle edge cases that lead to mathematical operations resulting in division by zero errors. This fundamental programming flaw occurs because the implementation does not adequately sanitize or validate the parameters passed to these rendering functions, allowing malicious input to bypass normal error handling mechanisms. The divide-by-zero condition causes the X server daemon to crash and terminate unexpectedly, resulting in a complete denial of service for all graphical operations within the affected system.
The operational impact of CVE-2007-2437 extends beyond simple service disruption, as it affects the core graphical infrastructure that many applications depend upon for user interface functionality. When the X server daemon crashes, all running graphical applications cease to function properly, potentially affecting desktop environments, window managers, and any applications that rely on X11 for display operations. This vulnerability particularly impacts multi-user environments where authenticated access is already possible, as it allows attackers to maintain their access privileges while simultaneously causing system-wide graphical service failures. The vulnerability is classified under CWE-369 as a divide by zero error, which represents a common but dangerous class of programming flaws that can lead to service disruption and system instability.
The threat landscape for this vulnerability is particularly concerning as it requires only authenticated access to exploit, meaning that an attacker who has already gained legitimate credentials to the system can leverage this weakness to cause significant disruption. This characteristic aligns with ATT&CK technique T1499.004 for network denial of service, as the vulnerability enables an attacker to cause service disruption through carefully crafted inputs. The X Window System's widespread adoption across Unix-like operating systems means that this vulnerability could potentially affect numerous systems, from desktop workstations to server environments that rely on graphical interfaces. Organizations running affected versions of X.org X Window System should consider this vulnerability as a high-priority concern due to its ability to cause complete graphical service failures and the relative ease with which authenticated attackers can exploit it.
Mitigation strategies for CVE-2007-2437 primarily focus on updating to patched versions of the X.org X Window System, as the vulnerability was resolved in subsequent releases that included proper input validation and error handling for the affected functions. System administrators should prioritize upgrading their X server implementations to versions that contain the necessary security patches, which typically include enhanced parameter validation and proper handling of edge cases that could lead to division by zero errors. Additionally, implementing network segmentation and access controls can help limit the potential impact of authenticated exploitation attempts, while monitoring for unusual X server behavior can aid in early detection of exploitation attempts. Organizations should also consider implementing application-level restrictions that limit the ability of authenticated users to submit potentially malicious input to rendering functions, although the most effective approach remains maintaining up-to-date system software versions with proper security patches applied.