CVE-2022-27008 in njs
Summary
by MITRE • 04/14/2022
nginx njs 0.7.2 is vulnerable to Buffer Overflow. Type confused in Array.prototype.concat() when a slow array appended element is fast array.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/20/2022
The vulnerability identified as CVE-2022-27008 affects nginx njs version 0.7.2 and represents a critical buffer overflow condition that arises from type confusion within the Array.prototype.concat() method. This flaw specifically manifests when processing arrays containing mixed element types where a slow array with appended elements interacts with a fast array during concatenation operations. The underlying issue stems from improper handling of array element type transitions and memory management during JavaScript array operations within the nginx njs runtime environment.
The technical implementation of this vulnerability exploits the fundamental differences between fast and slow arrays in JavaScript engines. Fast arrays are optimized for homogeneous element types and store elements directly in contiguous memory locations, while slow arrays accommodate heterogeneous elements and use hash tables or other data structures for storage. When Array.prototype.concat() processes a scenario where a slow array with appended elements is combined with a fast array, the engine fails to properly validate type consistency, leading to memory corruption that can result in buffer overflow conditions. This type confusion allows attackers to manipulate memory layout and potentially execute arbitrary code.
The operational impact of this vulnerability extends beyond typical web server exploitation scenarios as it affects the nginx njs JavaScript runtime environment that powers various nginx modules and functionalities. Attackers could leverage this vulnerability through maliciously crafted JavaScript code submitted to nginx instances running njs, potentially compromising server integrity and enabling unauthorized access to sensitive data. The vulnerability is particularly concerning because it operates at the JavaScript engine level rather than the application layer, making traditional web application firewalls and security measures less effective in preventing exploitation. This flaw could be exploited in contexts where nginx serves dynamic content through njs or where JavaScript-based configurations are processed.
Mitigation strategies for CVE-2022-27008 should prioritize immediate patching of nginx njs installations to version 0.7.3 or later, which contains the necessary fixes for the type confusion issue. Organizations should also implement runtime monitoring to detect anomalous array operations and memory access patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions and improper type handling, while its exploitation techniques correspond to ATT&CK tactics such as T1059.007 for scripting and T1595.001 for reconnaissance through network scanning. Security teams should also consider implementing strict input validation for all JavaScript code executed within nginx environments and regularly audit njs-based configurations for potential exploitation vectors.