CVE-2017-9814 in Cairo
Summary
by MITRE
cairo-truetype-subset.c in cairo 1.15.6 and earlier allows remote attackers to cause a denial of service (out-of-bounds read) because of mishandling of an unexpected malloc(0) call.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/26/2019
The vulnerability identified as CVE-2017-9814 resides within the cairo graphics library version 1.15.6 and earlier, specifically in the cairo-truetype-subset.c component. This issue represents a critical security flaw that can be exploited remotely to trigger a denial of service condition through an out-of-bounds read operation. The vulnerability stems from improper handling of memory allocation scenarios where the system encounters an unexpected malloc(0) call during the processing of TrueType font subsetting operations.
The technical root cause of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations. When the cairo library processes font data, it performs memory allocation operations that may result in a malloc(0) call under certain malformed input conditions. The library fails to properly validate or handle this specific allocation scenario, leading to memory access violations that manifest as out-of-bounds reads. This memory corruption occurs during the subset processing of TrueType fonts, where the library attempts to manipulate font data structures without adequate bounds checking or allocation validation.
From an operational perspective, this vulnerability presents significant risks to systems that utilize cairo for rendering graphics, particularly those that process untrusted font data from web browsers, document viewers, or other applications that might encounter malformed TrueType fonts. Attackers can craft malicious font files that, when processed by vulnerable cairo versions, will trigger the out-of-bounds read condition and subsequently cause the application to crash or become unresponsive. This denial of service can affect web browsers, desktop applications, and server-side rendering systems that depend on cairo for graphics processing, potentially leading to widespread service disruption across affected platforms.
The impact of this vulnerability extends beyond simple service disruption as it represents a potential pathway for more sophisticated attacks that could be combined with other exploits to achieve arbitrary code execution. Security researchers have categorized this issue under ATT&CK technique T1203, which covers exploitation of software vulnerabilities for privilege escalation and system compromise. Organizations using affected versions of cairo should implement immediate mitigations including patching to the latest stable releases, implementing input validation for font data processing, and deploying network segmentation to limit exposure of vulnerable applications. Additionally, system administrators should monitor for unusual application crashes or performance degradation that might indicate exploitation attempts, while also ensuring that font processing components are isolated from critical system functions to limit potential attack surface expansion.
This vulnerability highlights the importance of robust memory management practices in graphics libraries and the need for comprehensive input validation in font processing pipelines. The flaw demonstrates how seemingly benign memory allocation operations can lead to critical security implications when proper error handling and bounds checking mechanisms are absent from the implementation. Organizations should prioritize updating to patched versions of cairo while also implementing defensive coding practices that prevent similar issues in custom graphics processing components.