CVE-2026-33202 in activestorage
Summary
by MITRE • 03/24/2026
Active Storage allows users to attach cloud and local files in Rails applications. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, Active Storage's `DiskService#delete_prefixed` passes blob keys directly to `Dir.glob` without escaping glob metacharacters. If a blob key contains attacker-controlled input or custom-generated keys with glob metacharacters, it may be possible to delete unintended files from the storage directory. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.
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Analysis
by VulDB Data Team • 05/28/2026
Active Storage represents a critical component within Ruby on Rails applications that enables developers to handle file attachments using both local and cloud storage systems. This functionality has become integral to modern web applications where users can upload and manage various types of media content. The vulnerability identified in CVE-2026-33202 specifically targets the DiskService implementation within Active Storage, exposing applications to potential unauthorized file deletion operations. The flaw exists in how the system processes blob keys when performing cleanup operations, creating a dangerous path for malicious actors to exploit.
The technical flaw resides in the `DiskService#delete_prefixed` method which directly passes blob keys to the `Dir.glob` function without proper sanitization of glob metacharacters. This design oversight allows attackers to craft blob keys containing special characters such as asterisks, question marks, or square brackets that are interpreted by the glob pattern matching system. When these malicious keys are processed through `Dir.glob`, the system expands the patterns to match multiple files in the storage directory, resulting in unintended file deletions. The vulnerability demonstrates a classic path traversal and glob injection issue that has been documented under CWE-22 and CWE-77 in the Common Weakness Enumeration catalog.
The operational impact of this vulnerability extends beyond simple data loss scenarios, as it can potentially compromise entire storage directories and lead to service disruption. Attackers exploiting this weakness could target specific file patterns within the storage system, deleting critical application files or user data in a targeted manner. The vulnerability affects applications using Rails versions prior to 8.1.2.1, 8.0.4.1, and 7.2.3.1, making it particularly concerning for organizations maintaining legacy systems. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1485 which involves data destruction through file deletion and manipulation. The impact can be amplified when applications store sensitive user data or configuration files in the same storage directories, potentially leading to complete system compromise or data breaches.
Organizations should prioritize immediate patching of affected Rails applications to mitigate this vulnerability, with the recommended versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 providing the necessary security fixes. Additional mitigations include implementing proper input validation for blob keys, sanitizing user-provided data before storage, and monitoring storage directory access patterns for anomalous deletion activities. Security teams should also consider implementing file access controls and regular audits of storage systems to detect potential exploitation attempts. The vulnerability serves as a reminder of the importance of proper input sanitization in file system operations and the critical need for security reviews of storage handling components in web applications.