SFTPGo Authorization and Input Validation

SFTPGo versions prior to 2.7.1 contain a path normalization vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory) that allows authenticated attackers to bypass folder-level permissions and escape Virtual Folder boundaries through crafted file paths. An attacker with valid credentials can exploit this authorization bypass to access files and directories beyond their intended scope. The vulnerability has been patched in version 2.7.1 with strict edge-level path normalization, and while no public POC or KEV status has been disclosed, the CVSS 5.3 (network-accessible, low complexity) and requirement for prior authentication suggest this is a real but moderate-priority issue.

Denial-of-service vulnerability in Gokapi, a file-sharing server, wherein an authenticated attacker can send unbounded request bodies to an API endpoint without size restrictions, causing out-of-memory (OOM) conditions that crash the service and deny access to all users. The vulnerability requires valid authentication credentials but no special privileges, and is classified as high-severity (CVSS 6.5) due to guaranteed availability impact. Patch availability exists in version 2.2.4 and later.

A validation bypass in the chunked file upload completion logic for file requests allows attackers to circumvent per-request file size limits by splitting oversized files into smaller chunks that individually pass validation. Attackers with access to a public file request link can sequentially upload chunks to exceed the administrator-configured MaxSize limit, uploading files up to the server's global MaxFileSizeMB threshold. This enables unauthorized storage consumption and potential service disruption through storage exhaustion, though no data exposure or privilege escalation occurs; the vulnerability carries a CVSS score of 4.3 with EPSS and KEV status not currently indicated as critical, suggesting limited real-world exploitation pressure despite straightforward attack mechanics.

SFTPGo versions before v2.7.1 suffer from improper input validation in dynamic group path handling, where placeholder substitution (e.g., %username%) fails to sanitize relative path traversal sequences. An authenticated attacker with user creation privileges can craft a malicious username containing path traversal components (such as ../) to escape the intended directory structure and access parent directories, achieving unauthorized directory traversal with low to moderate impact on confidentiality and integrity. The vulnerability requires authenticated access and is not listed as actively exploited in known exploit databases, though the fix availability and moderate CVSS score suggest it warrants prompt patching.

An insufficient authorization check in a file replace API allows authenticated users with basic list and replace permissions to delete other users' files by abusing the deleteNewFile flag, bypassing the intended delete permission requirement. This affects any system implementing this vulnerable API pattern where permission checks are not properly enforced at the API endpoint level. While the CVSS score of 4.1 is moderate, the vulnerability requires high privilege level (authenticated user with PERM_REPLACE and PERM_LIST) and results in integrity impact through unauthorized file deletion across user boundaries.