CVE-2020-5256Network attack vector

Authenticated code execution via PHP image uploads

Published Mar 9, 2020 · Updated Aug 4, 2024

Unrestricted file upload in BookStack before 0.25.5 allows remote authenticated users to execute PHP code through image upload endpoints. The endpoints accepted PHP-capable files, including alternate PHP extensions and multiple-extension names, into web-accessible storage where a web server could execute them. Image-upload permission and executable local storage are required; successful code runs with the PHP process permissions and can read its accessible files.

CVSS severity7.9
High
EPSS probability1.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Unrestricted file upload in BookStack before 0.25.5 allows remote authenticated users to execute PHP code through image upload endpoints. The endpoints accepted PHP-capable files, including alternate PHP extensions and multiple-extension names, into web-accessible storage where a web server could execute them. Image-upload permission and executable local storage are required; successful code runs with the PHP process permissions and can read its accessible files.

The record

CVE
CVE-2020-5256
Published
Mar 9, 2020
Updated
Aug 4, 2024
Vendor
BookStack
Product
BookStack
Classifications
CWE-95, CWE-434, T1190, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 9, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.25.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

BookStack · BookStackversion=< 0.25.5

Published CVSS scores

7.9GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:L
9.0NIST NVDAV:N/AC:L/Au:S/C:C/I:C/A:C
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application
T1505.003Web Shell

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo