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CVE-2021-43820

MediumCVSS 5.9 / 10
Published Dec 14, 2021·Last modified Apr 11, 2026
Affected Components(0)

No affected components available

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.

Risk Scores
Base Score
5.9

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. 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 high impact on the confidentiality of the information.

Threat Intelligence
5.4

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.96%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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