CVE-2021-43820

Permissions check bypass in Seafile

MEDIUM
5.9
CVSS Score
Published: December 14, 2021 at 06:55 PM UTC
Updated: June 17, 2026 at 04:11 AM UTC
2 products affected across 2 vendorsSeafile ServerSeafile Server

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Severity
MEDIUM5.9
Exploit prediction
EPSS 1.0%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 8.0.15v < 8.0.89.0.0 ≤ v < 9.0.2
Affected range stops below 8.0.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.0.8, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.0.2, so it looks safe — our inference, not a vendor statement
v < 8.0.15v < 8.0.8
Affected range stops below 8.0.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.0.8, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-639

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