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GHSA-jrf2-h5j6-3rrq
No affected components available
Impact
First, a little bit of background. So, in the beginning, Bunkum's AuthenticationService only supported injecting IUsers. However, as Refresh and SoundShapesServer implemented permissions systems support for injecting ITokens into endpoints was added. All was well until 4.0.
Bunkum 4.0 then changed to enforce relations between ITokens and IUsers. This wasn't implemented in a very good way in the AuthenticationService, and ended up breaking caching in such a way that cached tokens would persist after the lifetime of the request - since we tried to cache both tokens and users. From that point until now, from what I understand, Bunkum was attempting to use that cached token at the start of the next request once cached.
Naturally, when that token expired, downstream projects like Refresh would remove the object from Realm - and cause the object in the cache to be in a detached state, causing an exception from invalid use of IToken.User. So in other words, a use-after-free since Realm can't manage the lifetime of the cached token.
Security-wise, the scope is fairly limited, can only be pulled off on a couple endpoints given a few conditions, and you can't guarantee which token you're going to get. Also, the token would get invalidated properly if the endpoint had either a IToken usage or a IUser usage. User interaction is required as authenticated requests must be performed.
Patches
The fix is to just wipe the token cache after the request was handled, which is now in 4.2.1. I'd recommend that you update. Unfortunately, there are no real workarounds for other versions in the 4.X.X range.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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