CVE-2026-88023 in PHP Library
Summary
by MITRE • 09/10/2026
Improper neutralization of special elements in data query logic in the GridFS component of the MongoDB PHP Library can cause a caller-supplied structured file identifier to be interpreted as a query condition rather than as a literal identifier. An authenticated user who can influence the identifier passed by an affected application may obtain stored file content beyond the intended target or cause all GridFS file chunks in the affected bucket to be removed, rendering stored file content unreadable. The affected rename operation may also rename a stored file other than the intended target.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified involves improper neutralization of special elements within data query logic, specifically affecting the GridFS component of the MongoDB PHP Library. This flaw represents a classic instance where user-supplied input is not adequately sanitized before being incorporated into database queries or operations. In this context, the issue arises when an application passes a structured file identifier to the library for processing. Instead of treating this identifier strictly as a literal value used to locate specific data objects within the GridFS bucket, the underlying query logic interprets certain special elements contained within that input as part of a query condition or operator structure. This misinterpretation allows an attacker who can influence the identifier passed by the application to manipulate the scope and target of database operations beyond what was originally intended by the developer.
From a technical perspective, this behavior stems from how MongoDB handles document queries and updates. When special characters or specific data structures are present in input fields that are expected to be simple identifiers, they may trigger unintended query operators such as $gt, $lt, or equality checks against other fields within the database documents. Consequently, an authenticated user who has access to functions utilizing this vulnerable component can craft a malicious file identifier. By injecting these special elements, the attacker transforms what should be a targeted lookup into a broader or differently directed operation. This lack of strict type enforcement and input validation in the GridFS implementation creates a significant security gap that undermines the integrity of data retrieval and modification processes.
The operational impact of this vulnerability is severe due to its potential for both unauthorized information disclosure and destructive denial-of-service conditions. First, an attacker can exploit the misinterpreted query logic to obtain stored file content beyond the intended target. This means sensitive documents or binary large objects (BLOBs) that were not meant to be accessed by a specific user session could be retrieved, leading to data leakage. Second, the vulnerability allows for more destructive actions, such as causing all GridFS file chunks in an affected bucket to be removed. By manipulating the query logic to match multiple documents or using operators like $unset or $pullAll through the malformed identifier, an attacker can delete vast amounts of stored data, rendering it unreadable and effectively destroying critical application assets.
Furthermore, the vulnerability extends beyond simple retrieval and deletion to include integrity violations during file management operations. The affected rename operation may also be exploited to rename a stored file other than the intended target. This occurs because the identifier used as the basis for the rename command is subject to the same query interpretation flaw. An attacker could thus alter metadata or move files between directories incorrectly, potentially disrupting application workflows, causing confusion in data organization, or facilitating further attacks by misdirecting users to maliciously renamed resources that mimic legitimate ones.
This vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command and more specifically CWE-943 Improper Neutralization of Special Elements in Data Query Logic, which covers issues where user input is incorrectly interpreted as part of a query structure rather than data. In terms of the MITRE ATT&CK framework, this behavior corresponds to techniques involving Injection (T1190) and potentially Impact via Data Destruction or Exfiltration depending on the specific exploitation path taken by an adversary. The core issue lies in the failure to enforce strict boundaries between control structures and data payloads within database interactions.
To mitigate this risk, developers must ensure that all inputs passed to GridFS operations are strictly validated as literal identifiers before being processed by the library. This involves implementing rigorous input validation checks that reject any special characters or structured elements that could be interpreted as query operators. Utilizing parameterized queries where supported and avoiding dynamic construction of database commands from user-supplied data is essential. Additionally, applying principle of least privilege to database accounts used by the application can limit the blast radius if an exploitation attempt occurs, ensuring that even if a malicious identifier bypasses validation, it cannot perform destructive actions like deleting entire buckets or accessing unrelated sensitive files outside its authorized scope.