CVE-2026-110766 in Colanode
Summary
by MITRE • 10/14/2026
Colanode server through 0.4.7 contains a path traversal vulnerability that allows authenticated users to read arbitrary .jpeg files by supplying an encoded traversal sequence in avatarId. Attackers can send percent-encoded ../ sequences to GET /client/v1/avatars/:avatarId to escape the avatars directory and read .jpeg files belonging to other workspaces.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified in Colanode server versions up to 0.4.7 represents a critical path traversal flaw that compromises the integrity of file access controls within the application's avatar management subsystem. This security defect stems from insufficient validation and sanitization of user-supplied input, specifically the avatarId parameter utilized in the GET /client/v1/avatars/:avatarId endpoint. Although the system requires authentication to initiate requests, this barrier is bypassed by exploiting how the server processes encoded path sequences. The core technical failure lies in the application's inability to properly canonicalize or restrict file paths before accessing them on the underlying operating system. When an authenticated user submits a request containing percent-encoded traversal sequences such as ../ within the avatarId field, the server fails to strip these characters or validate that the resulting resolved path remains confined within the designated avatars directory. Consequently, the application interprets the encoded sequence literally and resolves it against the file system root or parent directories, allowing access to files outside the intended scope.
From a technical perspective, this vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The exploitation mechanism relies on HTTP percent-encoding to obfuscate directory traversal characters during transmission. While many modern web frameworks automatically decode these sequences before processing route parameters, the specific implementation in Colanode does not adequately sanitize the decoded path components against relative navigation commands. This oversight enables an attacker to construct malicious payloads that navigate up the directory hierarchy using ../ sequences. By carefully crafting these encoded strings, a remote authenticated user can traverse out of the restricted avatar storage area and access arbitrary .jpeg files stored elsewhere on the server's file system. The vulnerability is particularly dangerous because it targets image assets which are frequently cached or served directly by web servers, potentially exposing sensitive data such as personal identification information embedded in images from other workspaces if those directories share a common parent path accessible via traversal.
The operational impact of this flaw extends beyond simple unauthorized read access to arbitrary files. Since the vulnerability allows reading .jpeg files belonging to other workspaces, it constitutes a significant breach of multi-tenant isolation and data confidentiality. In collaborative platforms like Colanode, workspace boundaries are critical for maintaining privacy between different user groups or organizations. An attacker leveraging this flaw can exfiltrate sensitive visual content from competitors, internal corporate communications depicted in profile pictures, or any other image files stored on the server that fall within reach of the traversal path. This capability effectively neutralizes the security boundary intended to separate workspace data, leading to potential regulatory non-compliance regarding data protection and privacy laws such as GDPR or HIPAA if sensitive personal information is exposed. Furthermore, while the current description specifies reading .jpeg files, similar implementations often suffer from broader file inclusion issues that could potentially be extended to read other file types depending on server configuration and available extensions.
This vulnerability maps directly to several entries in the MITRE ATT&CK framework, specifically T1083: File and Directory Discovery and T1560: Archive Collected Data if an attacker were to systematically enumerate and download files for later analysis. The exploitation technique aligns with CWE-20: Improper Input Validation, as the application fails to validate that the input conforms to expected patterns or constraints before use in file system operations. To mitigate this risk, immediate remediation should focus on implementing strict allow-listing of permitted characters for the avatarId parameter and ensuring that all user-supplied paths are resolved using secure APIs such as os.path.realpath() followed by a check against an allowed base directory prefix. Developers must also ensure that input decoding occurs before validation checks rather than after, preventing encoded traversal sequences from bypassing security controls. Additionally, applying principle of least privilege to the application's file system access rights can limit the damage even if traversal is attempted. Upgrading to a patched version of Colanode where these path handling routines have been hardened is essential for restoring secure operation and maintaining trust in the platform's data isolation mechanisms.