What is CVE-2021-4194?

CVE-2021-4194 is a medium-severity vulnerability in Bookstackapp Bookstack, classified under Improper Access Control. CVSS score: 6.5/10. Published 2022-01-06.

How severe is CVE-2021-4194?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Auth bypass in Bookstackapp Bookstack

CVE-2021-4194

bookstack is vulnerable to Improper Access Control

Published 2022-01-06 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.007 (51.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Bookstackapp Bookstack
Bookstackapp Bookstackapp/bookstack — versions unspecified

Weakness classification (CWE)

References

huntr.dev/bounties/0bc8b3f7-9057-4eb7-a989-24cd5689f114 (Exploit, Third Party Advisory)
github.com/bookstackapp/bookstack/commit/cb0d674a71449de883713db2fcdccb6e108992… (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-4194?: CVE-2021-4194 is a medium-severity vulnerability in Bookstackapp Bookstack, classified under Improper Access Control. CVSS score: 6.5/10. Published 2022-01-06.
How severe is CVE-2021-4194?: Medium severity. CVSS v3 base score is 6.5 out of 10.