Security readout for executives and security teams
Plain-English summary
Mermaid versions before 8.11.0 had a cross-site scripting issue tied to the antiscript feature. If an application renders untrusted Mermaid diagrams, attacker-supplied content could execute script in a user's browser. The public record is sparse and does not provide CVSS, CWE, or detailed impact scoring.
Executive priority
Treat this as a dependency hygiene and user-content risk. Prioritize systems that render customer, employee, or public Mermaid input, especially authenticated portals where XSS could affect privileged sessions.
Technical view
CVE-2021-35513 describes XSS in Mermaid before 8.11.0 when antiscript is used. The referenced GitHub issue, pull request, and 8.11.0 release candidate indicate the issue was addressed upstream. Available sources do not provide exploit details, affected integrations, or formal severity metrics.
Likely exposure
Exposure is most likely where Mermaid before 8.11.0 is embedded and renders diagrams from users, customers, or other untrusted sources. Static sites or internal tools may still be exposed if they process untrusted diagram text.
Exploitation context
No source in the bundle indicates active exploitation, and CISA KEV status is false. The risk is contextual: XSS impact depends on whether untrusted Mermaid input reaches browsers and what privileges those browser sessions hold.
Researcher notes
The public source bundle confirms the vulnerability statement and upstream references but lacks CVSS, CWE, detailed root cause, and exploitation evidence. Validation should focus on dependency versioning and whether untrusted Mermaid diagrams are rendered.
Mitigation direction
- Upgrade Mermaid to 8.11.0 or later where available.
- Review vendor or application guidance for bundled Mermaid dependencies.
- Avoid rendering untrusted Mermaid content until updated.
- Restrict Mermaid input to trusted authors where immediate upgrade is unavailable.
Validation and detection
- Inventory applications and packages that include Mermaid.
- Confirm deployed Mermaid versions are 8.11.0 or later.
- Identify paths where users can submit Mermaid diagrams.
- Verify untrusted diagram rendering is disabled or upgraded.
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.
CVE-2021-35513 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/mermaid-js/mermaid/issues/2122CVE reference · x_refsource_MISC
- https://github.com/mermaid-js/mermaid/pull/2123CVE reference · x_refsource_MISC
- https://github.com/mermaid-js/mermaid/releases/tag/8.11.0-rc2CVE 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.