CVE-2015-1262 in Chrome
Summary
by MITRE
platform/fonts/shaping/HarfBuzzShaper.cpp in Blink, as used in Google Chrome before 43.0.2357.65, does not initialize a certain width field, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via crafted Unicode text.
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Analysis
by VulDB Data Team • 05/19/2022
The vulnerability identified as CVE-2015-1262 resides within the HarfBuzzShaper.cpp component of Blink engine, which serves as the rendering engine for Google Chrome browser. This flaw manifests in the platform/fonts/shaping/HarfBuzzShaper.cpp file where a specific width field fails to receive proper initialization during font shaping operations. The issue occurs when processing crafted Unicode text sequences that exploit the uninitialized memory state, creating potential security implications for users of affected Chrome versions prior to 43.0.2357.65. The vulnerability classifies under CWE-457 as an use of uninitialized variable, representing a fundamental programming error that can lead to unpredictable behavior in software systems.
The technical exploitation of this vulnerability involves sending specially crafted Unicode text to a target system running an affected Chrome version. When the browser attempts to render this text through the HarfBuzz shaping engine, the uninitialized width field causes memory corruption patterns that can trigger denial of service conditions. The uninitialized variable behavior creates a scenario where the application reads from memory locations containing arbitrary data, potentially leading to crashes or system instability. This type of vulnerability represents a classic example of how improper memory management can create security risks, as described in the ATT&CK framework under technique T1499 for network denial of service attacks. The vulnerability's impact extends beyond simple crashes to potentially allow for more sophisticated attacks depending on the memory state at the time of access.
The operational impact of CVE-2015-1262 affects users of Google Chrome versions below the patched threshold of 43.0.2357.65, creating a significant risk for organizations and individuals who remain on outdated browser versions. Remote attackers can leverage this vulnerability through web-based attacks without requiring user interaction, making it particularly dangerous in environments where users browse untrusted websites. The potential for unspecified other impacts suggests that beyond simple denial of service, this uninitialized variable could potentially enable information disclosure or privilege escalation scenarios depending on the specific memory layout and exploitation conditions. Organizations utilizing older Chrome versions face increased risk of system compromise, as this vulnerability can be exploited through web pages containing malicious Unicode content that triggers the faulty font shaping code path.
Mitigation strategies for CVE-2015-1262 primarily involve immediate patching of affected Chrome installations to version 43.0.2357.65 or later, which properly initializes the width field in the HarfBuzzShaper.cpp implementation. System administrators should implement comprehensive browser update policies to ensure all endpoints receive security patches promptly. Additional defensive measures include network-based protections such as web application firewalls that can detect and block suspicious Unicode text patterns, though these provide only partial protection given the vulnerability's nature. The fix implemented by Google addressed the root cause by ensuring proper initialization of the width field before use, following secure coding practices that align with industry standards for preventing uninitialized variable vulnerabilities. Organizations should also consider implementing browser hardening configurations and monitoring for unusual browser behavior that might indicate exploitation attempts. This vulnerability underscores the importance of proper memory management in security-critical software components and demonstrates how seemingly minor programming errors can create significant security risks in widely deployed applications.