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CVE-2020-5256

22
FAUCET Score

CVE-2020-5256 is a critical vulnerability affecting BookStack versions prior to 0.25.5, allowing authenticated users to upload malicious PHP files disguised as images. This remote code execution flaw grants attackers the permissions of the PHP process on the host system. With a CVSS score of 8.8 (HIGH), the vulnerability has a low attack complexity and can lead to complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation, public exploit code, or significant community discussion, immediate patching to version 0.25.5 or higher is strongly recommended to mitigate this severe risk.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.25.3CPE matchmatch criteria
cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.9HIGH

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
LOW
Exploitability Score
1.3
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.95%
Probability of exploitation in next 30 days
EPSS Percentile
78.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0195 is in the 76th percentile among its peer group of 17,822 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 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: 0.25.5

Vendor Advisories (1)

composerGHSA-g9rq-x4fj-f5hxhigh

Remote Code Execution Through Image Uploads in BookStack

Mar 13, 2020

References

github.com / BookStackApp/BookStack/releases/tag/v0.25.3
Release Notes
github.com / BookStackApp/BookStack/releases/tag/v0.25.4
Release Notes
github.com / BookStackApp/BookStack/releases/tag/v0.25.5
Release Notes
github.com / BookStackApp/BookStack/security/advisories/GHSA-g9rq-x4fj-f5hx
Third Party Advisory