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CVE-2021-4194

23
FAUCET Score

CVE-2021-4194 describes an Improper Access Control vulnerability affecting bookstackapp BookStack. This medium-severity flaw (CVSS 6.5) allows a low-privileged attacker to achieve high integrity impact over the network with low attack complexity, potentially leading to unauthorized data modification. There is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 21.12.1CPE matchmatch criteria
cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

4.3MEDIUM

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
0.71%
Probability of exploitation in next 30 days
EPSS Percentile
49.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0071 is in the 60th percentile among its peer group of 21,974 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

composerpatch availablevia ghsa
Product: ssddanbrown/bookstackFixed in: 21.12.1

Vendor Advisories (1)

composerGHSA-ghhm-xrwp-75m9medium

bookstack is vulnerable to Improper Access Control

Jan 8, 2022

References

github.com / bookstackapp/bookstack/commit/cb0d674a71449de883713db2fcdccb6e108992ad
ExploitThird Party Advisory
huntr.dev / bounties/0bc8b3f7-9057-4eb7-a989-24cd5689f114
ExploitThird Party Advisory