CVE-2015-8395 in PCRE
Summary
by MITRE
PCRE before 8.38 mishandles certain references, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted regular expression, as demonstrated by a JavaScript RegExp object encountered by Konqueror, a related issue to CVE-2015-8384 and CVE-2015-8392.
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Analysis
by VulDB Data Team • 06/28/2022
The vulnerability described in CVE-2015-8395 affects the Perl Compatible Regular Expressions library version 8.37 and earlier, representing a critical flaw in regular expression processing that can lead to denial of service conditions and potentially more severe consequences. This issue specifically involves the mishandling of certain references within regular expressions, creating a scenario where malformed patterns can trigger unexpected behavior in applications that utilize PCRE for pattern matching operations.
The technical flaw manifests when PCRE encounters specific types of references within regular expressions that cause the library to process these patterns incorrectly. These malformed references can lead to memory corruption, infinite loops, or other processing anomalies that ultimately result in application crashes or system instability. The vulnerability is particularly dangerous because it can be exploited through crafted regular expressions that appear legitimate to the parser but contain subtle constructs that trigger the flawed processing logic. The issue affects web browsers and other applications that rely on PCRE for JavaScript RegExp object processing, making it a widespread concern across multiple platforms and software implementations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable more sophisticated attacks depending on the environment where the vulnerable library is deployed. When exploited through a JavaScript RegExp object in Konqueror, the vulnerability demonstrates how seemingly innocuous web content can be weaponized to disrupt service availability. The flaw is related to CVE-2015-8384 and CVE-2015-8392, indicating a broader pattern of issues within the PCRE library that affect regular expression handling and processing. This interconnectedness suggests that attackers may be able to combine multiple vulnerabilities to achieve more significant impacts, potentially leading to privilege escalation or information disclosure depending on the target system architecture.
Organizations and developers should prioritize updating their PCRE installations to version 8.38 or later to mitigate this vulnerability, as the patch addresses the specific reference handling issues that trigger the problematic behavior. System administrators should also consider implementing input validation and sanitization measures to prevent malformed regular expressions from reaching the PCRE processing layer, particularly in web applications that accept user input for pattern matching operations. The vulnerability aligns with CWE-129, which addresses improper handling of input validation and processing, and may be categorized under ATT&CK technique T1059.007 for abuse of scripting languages and regular expressions to execute malicious code or cause system instability. Additionally, this vulnerability represents a classic example of a resource exhaustion attack pattern where crafted input causes the system to consume excessive processing resources, potentially leading to system-wide denial of service conditions.