CVE-2026-55661

TinaCMS rich-text (slatejson) rendering does not sanitize link/image URLs, allowing stored XSS via dangerous URL schemes

MEDIUM
4.8
CVSS Score
Published: July 1, 2026 at 08:44 PM UTC
Updated: July 6, 2026 at 04:16 PM UTC
2 products affected across 1 vendorTinacmsMdx

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Severity
MEDIUM4.8
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Tina is a headless content management system. In versions prior to @tinacms/mdx 2.1.7 and tinacms 3.9.3, rich-text parsing and the default link/image renderers did not sanitize the url field on Slate link/image nodes. Content containing javascript: or data:text/html URLs — including case-variant, whitespace-padded, and control-character-obfuscated forms — is rendered into href/src and executes when the content is viewed. Any actor able to author rich-text content (for example a lower-privileged editor, or imported/external content) can achieve stored XSS against editors and site viewers. This issue is fixed in versions @tinacms/mdx 2.1.7 and tinacms 3.9.3.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.1.7
Affected range stops below 2.1.7, so it looks safe — our inference, not a vendor statement
v < 3.9.3
Affected range stops below 3.9.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (2)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.8MEDIUMGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-79CWE-87

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