CVE-2026-88340 in YARA
Summary
by MITRE • 09/22/2026
An invalid pointer release vulnerability exists in YARA 4.5.8 during deserialization of compiled .yrc rule files. The vulnerability is caused by insufficient validation of external-variable pointers, which may lead to invalid free in yr_rules_destroy() or wild pointer access in yr_object_create(). An attacker can provide a specially crafted .yrc file that causes memory corruption and application crash.
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Analysis
by VulDB Data Team • 09/22/2026
The identified vulnerability represents a critical flaw within the YARA engine version 4.5.8, specifically targeting the deserialization process of compiled rule files with the .yrc extension. This issue stems from insufficient validation mechanisms applied to external-variable pointers during the parsing and loading phases. When an application processes these serialized rules, it fails to adequately verify the integrity and validity of pointer references before attempting to utilize them in memory management operations or object creation routines. This lack of rigorous input sanitization allows malformed data structures to bypass standard safety checks, leading directly to unsafe memory access patterns that compromise the stability and security of the host application running YARA for malware detection or file analysis tasks.
From a technical perspective, the core defect manifests in two distinct but related failure modes within the engine's internal logic. First, during the destruction phase handled by the yr_rules_destroy function, an invalid pointer release occurs because the system attempts to free memory addresses that were either never allocated correctly or have already been deallocated due to prior corruption. Second, and potentially more dangerous for exploitation scenarios, is the occurrence of wild pointer access within the yr_object_create routine. Here, the engine attempts to instantiate objects using pointers derived from unvalidated external variables in the .yrc file. If these pointers point to arbitrary memory locations rather than valid heap or stack segments, it results in undefined behavior that can be leveraged by an attacker to execute arbitrary code or cause a denial of service through segmentation faults and application crashes.
The operational impact of this vulnerability is significant for any organization relying on YARA rulesets for automated threat hunting or incident response. An adversary who controls the input data stream, such as one providing custom malware samples with embedded malicious rule definitions or manipulating configuration files that trigger rule loading, can exploit this flaw to disrupt security operations. By crafting a specially designed .yrc file containing malformed external-variable pointers, an attacker can induce memory corruption within the YARA process. This leads to immediate application termination, effectively creating a denial of service condition for any monitoring systems dependent on continuous scanning capabilities. Furthermore, in environments where rule files are sourced from untrusted or semi-trusted repositories without strict validation pipelines, this vulnerability could serve as an initial vector for more complex attacks if memory corruption is leveraged further through heap spraying techniques to achieve remote code execution.
To mitigate the risks associated with CVE details concerning invalid pointer release and wild pointer access in YARA 4.5.8, immediate action should be taken by upgrading to a patched version of the software where these validation checks have been strengthened. Security teams must also implement strict input validation policies for all .yrc files before they are processed by the engine, ensuring that only signed or verified rule sets from trusted sources are loaded into production environments. Additionally, deploying runtime application self-protection mechanisms and memory safety tools can help detect anomalous behavior indicative of exploitation attempts. From a classification standpoint, this vulnerability aligns with CWE-416 Use After Free regarding the invalid pointer release aspect and CWE-94 Improper Control of Generation of Code (Code Injection) or CWE-787 Out-of-bounds Write/Read concerning the wild pointer access, while its exploitation vector relates to ATT&CK technique T1059 Command and Scripting Interpreter if used in conjunction with other payloads for code execution.