Security readout for executives and security teams
Plain-English summary
BookStack versions before 0.30.4 let a user who can edit pages place malicious links, forms, or a redirecting meta tag into page content. Other users could then be redirected or have script run in their browser when interacting with that content.
Executive priority
Treat as high priority for any BookStack instance with broad editor access or sensitive internal users. Patch promptly, because successful abuse can expose session-context data or redirect users to attacker-controlled locations.
Technical view
This is stored XSS in BookStack page content handling. An authenticated editor could use javascript: URIs in links/forms, triggered by user click or submit, or insert a meta tag causing silent redirect on page visit. The vendor fixed display sanitization in 0.30.4.
Likely exposure
Exposure is limited to BookStack deployments running versions before 0.30.4, especially where page editing is available to many or semi-trusted users. Risk rises when administrators or privileged users routinely view user-edited pages.
Exploitation context
The bundle does not show active exploitation, and KEV is false. Exploitation requires page edit permission and victim interaction for the JavaScript path, but the redirect path may occur when a crafted page is visited.
Researcher notes
CVSS 3.1 is 7.7 with PR:L, UI:R, scope changed, and high confidentiality and integrity impact. Sources identify the fixed release and workaround, but this bundle does not provide evidence of exploitation in the wild.
Mitigation direction
- Upgrade BookStack to version 0.30.4 or later.
- Restrict page edit permissions to trusted users until upgraded.
- Use the vendor advisory guidance to identify dangerous stored content.
- Review vendor release notes before changing production instances.
Validation and detection
- Inventory BookStack instances and confirm each version is at least 0.30.4.
- Review who has page edit permissions in each instance.
- Use the advisory-provided SQL query to check for possible stored content.
- Confirm suspicious content is not displayed after upgrading.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-26211 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N1.35.8Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.7HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/BookStackApp/BookStack/releases/tag/v0.30.4CVE reference · x_refsource_MISC
- https://github.com/BookStackApp/BookStack/security/advisories/GHSA-r2cf-8778-3jgpCVE reference · x_refsource_CONFIRM
- https://github.com/BookStackApp/BookStack/commit/bbd1384acbe7e52c21f89af69f2dc391c95dbf54CVE reference · x_refsource_MISC
- https://www.bookstackapp.com/blog/beta-release-v0-30-4/CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.