Skip to main content
No exploitation reportedFix available

CVE-2020-5256

No exploitation reported by the sources we read.

  • Published2020-03-09
  • Fixed in0.25.3
  • WeaknessCWE-434 · CWE-95

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2020-03-0916:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-5256?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-5256?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Bookstackapp bookstack
BranchAffectedFixed in
0.25< 0.25.30.25.3
ssddanbrown/bookstack
BranchAffectedFixed in
0.25< 0.25.50.25.5

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Bookstackapp bookstack to 0.25.3

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CNACVSS 3.17.9read 2026-10-23
  • NVDCVSS 3.18.8read 2026-10-23
  • NVDCVSS 2.09read 2026-10-23
  • CNAweakness (CWE)CWE-95read 2026-10-23
  • NVDweakness (CWE)CWE-434read 2026-10-23
  • FIRST EPSSEPSS score2.0 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2020-03-09
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2020-5256?

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.

Is CVE-2020-5256 actively exploited?

Active exploitation of CVE-2020-5256 has not been confirmed. Its EPSS score was 2.0% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-5256?

CVE-2020-5256 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Running ssddanbrown/bookstack? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this productCISA KEV additions, October 2026Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database