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CVE-2021-4119

45
FAUCET Score

CVE-2021-4119 is a critical improper access control vulnerability affecting BookStack, specifically the bookstackapp product. With a CVSS score of 9.8, this flaw allows unauthenticated attackers to remotely execute arbitrary code with low attack complexity, leading to complete compromise of confidentiality, integrity, and availability. While no public exploits or active exploitation have been observed, and community discussion is minimal, its high severity warrants immediate attention.

Impacted Technologies

VendorProductVersion(s)CPE
<= 21.11.2CPE matchmatch criteria
cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
26.89%
Probability of exploitation in next 30 days
EPSS Percentile
97.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.2689 is in the 95th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: ssddanbrown/bookstackFixed in: 21.11.3
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-9c5c-5j4h-8q2cmedium

BookStack is vulnerable to Improper Access Control.

Dec 16, 2021

References

github.com / bookstackapp/bookstack/commit/e765e618547c92f4e0b46caca6fb91f0174efd99
PatchThird Party Advisory
huntr.dev / bounties/135f2d7d-ab0b-4351-99b9-889efac46fca
ExploitPatchThird Party Advisory