CVE-2026-86285Public exploitNetwork attack vector

Attachment metadata disclosure via missing page-view check

Published Sep 7, 2026 · Updated Sep 9, 2026

Improper access control in BookStack 26.05.0 through 26.05.2 allows remote authenticated users to read restricted attachment metadata. AttachmentController::getUpdateForm retrieves an attachment by numeric ID and renders its name and external-link URL without checking PageView permission. Exploitation requires PageUpdate and AttachmentCreate rights combined with denied PageView access; attachment content and modification remain unavailable.

CVSS severityUnavailable
Unscored
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Improper access control in BookStack 26.05.0 through 26.05.2 allows remote authenticated users to read restricted attachment metadata. AttachmentController::getUpdateForm retrieves an attachment by numeric ID and renders its name and external-link URL without checking PageView permission. Exploitation requires PageUpdate and AttachmentCreate rights combined with denied PageView access; attachment content and modification remain unavailable.

The record

CVE
CVE-2026-86285
Published
Sep 7, 2026
Updated
Sep 9, 2026
Vendor
BookStack
Product
BookStack
Classifications
CWE-284, CWE-266, T1213
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=26.05.0
  2. Affected versionversion=26.05.1
  3. Affected versionversion=26.05.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

BookStack · BookStackversion=26.05.0; version=26.05.1; version=26.05.2

Published CVSS scores

4.0VulDB CNAAV:N/AC:L/Au:S/C:P/I:N/A:N/E:POC/RL:OF/RC:C
4.3VulDB CNACVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C
5.3VulDB CNACVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P
4.3VulDB CNACVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
CWE-266Incorrect Privilege Assignment
T1213Data from Information Repositories

Public exploit references

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

Technologies

Your stack

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Your stack

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