What is CVE-2021-3916?

CVE-2021-3916 is a medium-severity vulnerability in Bookstackapp Bookstack, classified under Path Traversal. CVSS score: 6.5/10. Published 2021-11-05.

How severe is CVE-2021-3916?

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

Path Traversal in Bookstackapp Bookstack

CVE-2021-3916

bookstack is vulnerable to Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Vulnerability class: Path Traversal (Directory Traversal)

Published 2021-11-05 · 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:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.012 (68.0th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 68.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Bookstackapp Bookstack
Bookstackapp Bookstackapp/bookstack — versions unspecified

Weakness classification (CWE)

CWE-22 — Path Traversal

References

huntr.dev/bounties/0be32e6b-7c48-43f0-9cec-433000ad8f64 (Exploit, Patch, Third Party Advisory, Issue Tracking)
github.com/bookstackapp/bookstack/commit/43830a372fc51a8793199d04a34c3f4ebdfccc… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3916?: CVE-2021-3916 is a medium-severity vulnerability in Bookstackapp Bookstack, classified under Path Traversal. CVSS score: 6.5/10. Published 2021-11-05.
How severe is CVE-2021-3916?: Medium severity. CVSS v3 base score is 6.5 out of 10.