CVE-2021-43820 Permissions check bypass in Seafile
Attackers with a valid sync token can access data from any known library by bypassing library-specific authorization checks in Seafile server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-43820?
CVE-2021-43820 is a high-severity missing authorization vulnerability in haiwen seafile-server, published on 14 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Seafile is an open source cloud storage system. A sync token is used in Seafile file syncing protocol to authorize access to library data. To improve performance, the token is cached in memory in seaf-server. Upon receiving a token from sync client or SeaDrive client, the server checks whether the token exist in the cache. However, if the token exists in cache, the server doesn't check whether it's associated with the specific library in the URL. This vulnerability makes it possible to use any valid sync token to access data from any **known** library. Note that the attacker has to first find out the ID of a library which it has no access to. The library ID is a random UUID, which is not possible to be guessed. There are no workarounds for this issue.
Weakness: CWE-639
Which versions are affected by CVE-2021-43820?
It affects 1 product.
Products include Seafile Seafile Server.
How do I fix CVE-2021-43820?
No fix has been published for CVE-2021-43820 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2021-43820 being exploited?
There is no known exploitation of CVE-2021-43820 in the wild and no public exploit code.
Other vulnerabilities in haiwen seafile-server
Sources
Also known as GHSA-m3wc-jv6r-hvv8.