Summary
Tina's tina-markdown component renders a rich-text URL directly as an anchor href without validating its scheme. A content author may store a script-capable link that executes attacker-controlled code in the site's origin when a visitor clicks it, potentially exposing same-origin data and editor or administrator credentials.
Tina's tina-markdown component renders a rich-text URL directly as an anchor href without validating its scheme. A content author may store a script-capable link that executes attacker-controlled code in the site's origin when a visitor clicks it, potentially exposing same-origin data and editor or administrator credentials.
Affected context
The issue occurs in Tina deployments that use the vulnerable tina-markdown web component to render author-controlled rich-text links. Risk is present when content authors can store URL values and visitors, particularly authenticated editors or administrators, can access rendered content on the same origin as the TinaCMS administration interface.
The issue occurs in Tina deployments that use the vulnerable tina-markdown web component to render author-controlled rich-text links. Risk is present when content authors can store URL values and visitors, particularly authenticated editors or administrators, can access rendered content on the same origin as the TinaCMS administration interface.
Exploit preconditions
- Attack surface: Rendered rich-text links in the tina-markdown component
- Required access: Permission to create or modify content containing a link
- Trigger point: A visitor clicks the rendered link
- Why exploitation is possible: The component assigns the stored URL directly to an anchor href without restricting script-capable URL schemes
- Attack surface: Rendered rich-text links in the tina-markdown component
- Required access: Permission to create or modify content containing a link
- Trigger point: A visitor clicks the rendered link
- Why exploitation is possible: The component assigns the stored URL directly to an anchor href without restricting script-capable URL schemes
Why this happens
The underlying bug is inadequate output handling of a URL-bearing rich-text value. Assigning an untrusted URL directly to an anchor href without scheme validation permits script-capable schemes to reach the browser as active link destinations.
This maps primarily to CWE-79: Improper Neutralization of Input During Web Page Generation, because attacker-controlled content is rendered in a way that enables script execution. It is also related to CWE-83: Improper Neutralization of Script-Related HTML Tags in a Web Page, reflecting unsafe handling of script-capable link content.
The underlying bug is inadequate output handling of a URL-bearing rich-text value. Assigning an untrusted URL directly to an anchor href without scheme validation permits script-capable schemes to reach the browser as active link destinations.
This maps primarily to CWE-79: Improper Neutralization of Input During Web Page Generation, because attacker-controlled content is rendered in a way that enables script execution. It is also related to CWE-83: Improper Neutralization of Script-Related HTML Tags in a Web Page, reflecting unsafe handling of script-capable link content.
Potential impact
- An attacker-controlled script may execute in the site's origin
- Same-origin application data could be read or modified
- Session-related information or exposed credentials may be accessed
- Editor or administrator accounts could be targeted through trusted content
- Content integrity and administrative workflows could be compromised
- An attacker-controlled script may execute in the site's origin
- Same-origin application data could be read or modified
- Session-related information or exposed credentials may be accessed
- Editor or administrator accounts could be targeted through trusted content
- Content integrity and administrative workflows could be compromised
General mitigation guidance
Mitigation generally focuses on treating content-authored URLs as untrusted data and enforcing safe link policies at the rendering boundary.
Common defensive patterns include:
- Allowing only explicitly approved schemes, such as HTTPS, for rendered links
- Rejecting or neutralizing script-capable and otherwise unexpected URL schemes
- Applying URL validation and normalization before assigning values to href attributes
- Enforcing contextual output encoding and safe DOM APIs
- Separating public content origins from administrative interfaces where practical
- Limiting administrative privileges and reducing the sensitivity of data exposed to browser-accessible scripts
- Applying content validation consistently on both authoring and rendering paths
Mitigation generally focuses on treating content-authored URLs as untrusted data and enforcing safe link policies at the rendering boundary.
Common defensive patterns include:
- Allowing only explicitly approved schemes, such as HTTPS, for rendered links
- Rejecting or neutralizing script-capable and otherwise unexpected URL schemes
- Applying URL validation and normalization before assigning values to href attributes
- Enforcing contextual output encoding and safe DOM APIs
- Separating public content origins from administrative interfaces where practical
- Limiting administrative privileges and reducing the sensitivity of data exposed to browser-accessible scripts
- Applying content validation consistently on both authoring and rendering paths
How teams detect issues like this
Organizations can detect this class of issue through:
- Static analysis for direct assignment of untrusted values to href and similar URL-bearing attributes
- Code review checks for missing URL scheme allowlists and inconsistent output validation
- Dynamic tests using representative script-capable schemes in content-rendering paths
- Content security policies that restrict script execution and report violations
- Repository policies requiring safe link components or centralized URL validation
- Automated security review tools that identify DOM-based and stored cross-site scripting patterns
Organizations can detect this class of issue through:
- Static analysis for direct assignment of untrusted values to href and similar URL-bearing attributes
- Code review checks for missing URL scheme allowlists and inconsistent output validation
- Dynamic tests using representative script-capable schemes in content-rendering paths
- Content security policies that restrict script execution and report violations
- Repository policies requiring safe link components or centralized URL validation
- Automated security review tools that identify DOM-based and stored cross-site scripting patterns
