CVE-2021-3987 Improper Access Control in janeczku/calibre-web

Medium 5.4 Published 15 Nov 2024 Updated 15 Nov 2024

Users without public shelf permissions can create public shelves due to missing authorization checks in Calibre Web.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2021-3987?

CVE-2021-3987 is a medium-severity missing authorization vulnerability in janeczku/calibre-web, published on 15 Nov 2024. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

An improper access control vulnerability exists in janeczku/calibre-web. The affected version allows users without public shelf permissions to create public shelves. The vulnerability is due to the `create_shelf` method in `shelf.py` not verifying if the user has the necessary permissions to create a public shelf. This issue can lead to unauthorized actions being performed by users.

Weakness: CWE-862, CWE-284

Which versions are affected by CVE-2021-3987?

3 open source packages ship an affected version, including calibreweb. It affects 1 product.

Package	Affected	Fixed in
`calibreweb` PyPI	All versions	`0.6.15`
`calibreweb` PyPI	All versions	`0.6.15`
`calibreweb` PyPI	All versions	`0.6.15`

Products include Janeczku Calibre-Web.

How do I fix CVE-2021-3987?

Upgrade calibreweb to 0.6.15 or later.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2021-3987 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-3987 exists.

Sources

Also known as GHSA-fj5v-w2jp-wqvj, PYSEC-2026-1229.