Security readout for executives and security teams
Plain-English summary
Calibre-web versions 0.6.0 through 0.6.12 allow stored cross-site scripting in book metadata descriptions. A user who can edit metadata can save malicious JavaScript that runs when another user opens the file. Business impact is mainly account/session exposure or unauthorized actions in the victim’s browser.
Executive priority
Treat as a moderate-priority patching item. Escalate if Calibre-web is internet-facing, used by many editors, or contains sensitive user sessions. It does not warrant emergency handling based on the provided exploitation evidence.
Technical view
The issue is CWE-79 stored XSS in the Calibre-web Metadata description field. CVSS 3.1 is 5.4: network-reachable, low complexity, low privileges required, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact.
Likely exposure
Exposure is likely limited to Calibre-web deployments running 0.6.0 through 0.6.12 where users can edit metadata. Risk is higher for shared or internet-accessible libraries with multiple editors or untrusted contributors.
Exploitation context
The source bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation requires authenticated metadata edit access and a victim opening the affected file, so this is not unauthenticated drive-by compromise.
Researcher notes
Focus validation on stored rendering of the Metadata description field and privilege boundaries around metadata editing. The referenced commit is the best source for the code-level fix, but the bundle does not provide a named fixed release version.
Mitigation direction
- Identify all Calibre-web deployments and versions.
- Upgrade to a vendor release containing the referenced upstream fix.
- If upgrade timing is unclear, review current vendor guidance before changing compensating controls.
- Restrict metadata editing to trusted users until patched.
- Review existing metadata descriptions for suspicious scripts or unexpected HTML.
Validation and detection
- Confirm deployed Calibre-web versions are outside 0.6.0 through 0.6.12.
- Verify metadata description rendering is escaped or sanitized after remediation.
- Check who has metadata edit privileges in each deployment.
- Review application logs for unusual metadata edits before patching.
- Test remediation in a non-production instance without using offensive payloads.
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 lookupCVE-2021-25964 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
- Medium
- CVSS
- 5.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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:L/PR:L/UI:R/S:C/C:L/I:L/A:N2.32.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.4MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25964CVE reference · x_refsource_MISC
- https://github.com/janeczku/calibre-web/commit/32e27712f0f71fdec646add20cd78b4ce75acfceCVE 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.