CVE-2021-46495 in Jsish
Summary
by MITRE • 01/28/2022
Jsish v3.5.0 was discovered to contain a heap-use-after-free via DeleteTreeValue in src/jsiObj.c. This vulnerability can lead to a Denial of Service (DoS).
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Analysis
by VulDB Data Team • 01/30/2022
The vulnerability identified as CVE-2021-46495 affects Jsish version 3.5.0, a JavaScript interpreter implementation that provides both command-line and embedded scripting capabilities. This security flaw resides within the DeleteTreeValue function located in the src/jsiObj.c source file, representing a heap-use-after-free condition that fundamentally compromises memory management integrity. The issue manifests when the interpreter attempts to free memory that has already been deallocated, creating a scenario where subsequent memory operations may access invalid memory locations.
The technical implementation of this vulnerability stems from improper memory management within the object tree deletion process. When Jsish processes certain JavaScript constructs involving object hierarchies, the DeleteTreeValue function fails to properly track memory references, leading to situations where memory blocks are freed but still referenced by other data structures or pointers. This heap corruption occurs during the garbage collection phase when the interpreter attempts to clean up object trees, particularly when dealing with complex nested objects or circular references. The flaw represents a classic heap-use-after-free vulnerability as classified by CWE-416, which specifically addresses the use of memory after it has been freed.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it creates potential instability within the JavaScript interpreter environment. While the primary effect is a Denial of Service attack that can cause the interpreter to crash or become unresponsive, the underlying memory corruption could potentially be exploited by malicious actors to execute arbitrary code or escalate privileges. The vulnerability affects any system running Jsish 3.5.0 where JavaScript code is interpreted, including web applications, embedded systems, and command-line environments that utilize the interpreter. Attackers could leverage this flaw by crafting specific JavaScript payloads that trigger the problematic memory deletion sequence, potentially causing system instability or complete interpreter failure.
Mitigation strategies for this vulnerability should focus on immediate version updates to Jsish 3.5.1 or later, which contains the necessary patches to address the heap-use-after-free condition. Organizations should implement comprehensive patch management procedures to ensure all instances of the vulnerable software are updated promptly. Additionally, runtime monitoring and input validation should be enhanced to detect and prevent potentially malicious JavaScript code from triggering the vulnerable code paths. Security teams should consider implementing sandboxing techniques around JavaScript execution environments and establish memory integrity checks to identify potential heap corruption issues. From an ATT&CK framework perspective, this vulnerability aligns with T1059.007 for JavaScript execution and T1499.004 for network denial of service, making it a critical target for both defensive and offensive security teams to address through proper patching and monitoring protocols.