CVE-2021-3906
Unrestricted Upload of File with Dangerous Type in bookstackapp/bookstack
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Unrestricted Upload of File with Dangerous Type in bookstackapp/bookstack
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
- Record
CVE-2021-3906- CVSS 3.0
- 5.4 Medium
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-434
- Updated
- 2026-11-02
EUVDEUVD-2021-27134
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
- Record
EUVD-2021-27134- CVSS 3.0
- 5.4 Medium
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-qrmv-xr2h-3hrw No score
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
- Record
GHSA-qrmv-xr2h-3hrw- Weakness
- CWE-434
- Updated
- 2026-11-02
NVD
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
- Record
CVE-2021-3906- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - CVSS 3.0
- 5.4 Medium
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 4.0 Medium
AV:N/AC:L/Au:S/C:P/I:N/A:N - Weakness
- CWE-434
- Updated
- 2026-11-02
OSV
bookstack is vulnerable to Unrestricted Upload of File with Dangerous Type
- Record
CVE-2021-3906- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-3906 is a medium vulnerability (CVSS 5.4) in Bookstackapp Bookstack, published October 27, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.67%, the 52nd percentile. No source names a fixed version.