CVE-2026-32701 in qwik
Summary
by MITRE • 03/20/2026
Qwik is a performance-focused JavaScript framework. Versions prior to 1.19.2 improperly inferred arrays from dotted form field names during FormData parsing. By submitting mixed array-index and object-property keys for the same path, an attacker could cause user-controlled properties to be written onto values that application code expected to be arrays. When processing application/x-www-form-urlencoded or multipart/form-data requests, Qwik City converted dotted field names (e.g., items.0, items.1) into nested structures. If a path was interpreted as an array, additional attacker-supplied keys on that path—such as items.toString, items.push, items.valueOf, or items.length—could alter the resulting server-side value in unexpected ways, potentially leading to request handling failures, denial of service through malformed array state or oversized lengths, and type confusion in downstream code. This issue was fixed in version 1.19.2.
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Analysis
by VulDB Data Team • 03/26/2026
The vulnerability identified as CVE-2026-32701 affects the Qwik JavaScript framework, specifically impacting versions prior to 1.19.2. This security flaw resides in the framework's FormData parsing mechanism, where the system incorrectly handles dotted form field names during request processing. The issue manifests when applications process application/x-www-form-urlencoded or multipart/form-data requests, creating a scenario where the framework's interpretation of data structure can be manipulated by attackers through carefully crafted input. The root cause stems from how Qwik City handles nested data structures, particularly when converting dotted field names into nested objects or arrays.
The technical implementation of this vulnerability exploits the framework's array inference logic during FormData processing. When a path like items.0 or items.1 is encountered, Qwik attempts to determine whether the structure should be treated as an array or an object. However, the system fails to properly distinguish between these data types when mixed keys are present on the same path. An attacker can leverage this by submitting form data containing both array-indexed keys (items.0, items.1) and object property keys (items.toString, items.push, items.valueOf, items.length) for the same logical path. This creates a condition where user-controlled properties can be injected into values that application code expects to remain as arrays, fundamentally altering the data structure and potentially causing type confusion.
The operational impact of this vulnerability extends beyond simple data corruption, presenting significant risks to application stability and security. When processed through the vulnerable framework, malformed input can cause request handling failures, leading to denial of service conditions where the application becomes unresponsive to legitimate requests. The vulnerability also enables attackers to manipulate array state through oversized lengths or malformed array structures, potentially causing memory exhaustion or unexpected application behavior. The type confusion aspect creates downstream security implications where code expecting array operations may inadvertently execute object methods, opening pathways for unexpected code execution or data manipulation. This vulnerability directly aligns with CWE-121, heap-based buffer overflow, and CWE-122, stack-based buffer overflow, as the improper array handling can lead to memory corruption scenarios.
Mitigation strategies for this vulnerability require immediate application updates to Qwik version 1.19.2 or later, which contains the necessary fixes for proper array inference during FormData parsing. Organizations should implement comprehensive input validation at the application boundary, specifically for form data processing, to prevent malformed dotted field names from reaching the framework's parsing layer. Additionally, security teams should consider implementing runtime checks that monitor for suspicious patterns in form field naming conventions, particularly when mixed array and object property keys appear on the same logical path. The ATT&CK framework categorizes this vulnerability under T1210, Exploitation of Remote Services, and T1070, Indicator Removal on Host, as it represents a server-side exploitation opportunity that can lead to service disruption and potentially more severe consequences if combined with other vulnerabilities. Organizations should also review their application's error handling mechanisms to ensure that malformed input does not expose internal application state or provide attackers with additional information about the system's structure.