What’s Vulnerable › Vulnerabilities

CVE-2021-3906: Unrestricted Upload of File with Dangerous Type in bookstackapp/bookstack

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-10-27 · updated 2026-06-17
• Weakness: CWE-434

Description

bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type

Affected products

• bookstackapp/bookstack: before 21.10.1 — fixed in 21.10.1

How to fix

Upgrade to a fixed version: bookstackapp/bookstack 21.10.1. Check the vendor advisory for mitigations.

References

• https://github.com/bookstackapp/bookstack/commit/64937ab826b56d086af9ecea532510d37520ebc8
• https://huntr.dev/bounties/f115bdf5-c06b-4627-a6fa-ba6904a43ba3
• https://github.com/bookstackapp/bookstack/commit/64937ab826b56d086af9ecea532510d37520ebc8
• https://huntr.dev/bounties/f115bdf5-c06b-4627-a6fa-ba6904a43ba3

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