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CVE-2020-5256· NVD / CVE Program· CNA GitHub_M

Remote Code Execution Through Image Uploads in BookStack

BookStack before version 0.25.5 has a vulnerability where a user could upload PHP files through image upload functions, which would allow them to execute code on the host system remotely. They would then have the permissions of the PHP process. This most impacts scenarios where non-trusted users are given permission to upload images in any area of the application. The issue was addressed in a series of patches in versions 0.25.3, 0.25.4 and 0.25.5. Users should upgrade to at least v0.25.5 to avoid this vulnerability.

HighCVSS 8.8 · v3.1—No exploit Fix available

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Published
Mar 9, 2020
Updated
Jun 16, 2026
EPSS
2.0% · 80th percentile
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Report tools

JSON

Action score

36

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.0%

CNA vs NVD score

NVD
8.8
CNA · GitHub_M
7.9
0.9 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
bookstackappbookstack

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • bookstackapp bookstackbefore 0.25.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • BookStackApp BookStack

    • < 0.25.5affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Packagistssddanbrown/bookstackbefore 0.25.50.25.5

Same product

bookstackapp: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-4119Improper Access Control in bookstackapp/bookstack
    47Plan
  • CVE-2026-84695BookStack before 26.05.4 Stored XSS via Drawing Upload
    37Monitor
  • CVE-2026-89022BookStack < 26.05.5 Authentication Bypass via Social Login Provider Confusion
    36Monitor
  • CVE-2026-82450BookStack before 26.05.4 Remote Code Execution via Book Cover
    34Monitor
  • CVE-2020-26211Cross-Site Scripting in BookStack
    34Monitor
  • CVE-2020-26210Cross-Site Scripting in BookStack
    34Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Packagist:ssddanbrown/bookstack0.25.5Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-95 · Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records