sftpgo is a full-featured and highly configurable event-driven file transfer solution. Server protocols: SFTP, HTTP/S, FTP/S, WebDAV. The OpenID Connect implementation allows authenticated users to brute force session cookies and thereby gain access to other users data, since the cookies are generated predictably using the xid library and are therefore unique but not cryptographically secure. This issue was fixed in version v2.6.4, where cookies are opaque and cryptographically secure strings. All users are advised to upgrade. There are no known workarounds for this vulnerability.
The product uses a broken or risky cryptographic algorithm or protocol.
Cryptographic algorithms are the methods by which data is scrambled to prevent observation or influence by unauthorized actors. Insecure cryptography can be exploited to expose sensitive information, modify data in unexpected ways, spoof identities of other users or devices, or other impacts. It is very difficult to produce a secure algorithm, and even high-profile algorithms by accomplished cryptographic experts have been broken. Well-known techniques exist to break or weaken various kinds of cryptography. Accordingly, there are a small number of well-understood and heavily studied algorithms that should be used by most products. Using a non-standard or known-insecure algorithm is dangerous because a determined adversary may be able to break the algorithm and compromise whatever data has been protected. Since the state of cryptography advances so rapidly, it is common for an algorithm to be considered “unsafe” even if it was once thought to be strong. This can happen when new attacks are discovered, or if computing power increases so much that the cryptographic algorithm no longer provides the amount of protection that was originally thought. For a number of reasons, this weakness is even more challenging to manage with hardware deployment of cryptographic algorithms as opposed to software implementation. First, if a flaw is discovered with hardware-implemented cryptography, the flaw cannot be fixed in most cases without a recall of the product, because hardware is not easily replaceable like software. Second, because the hardware product is expected to work for years, the adversary’s computing power will only increase over time.