CVE-2026-55661 is a medium-severity cross-site scripting (XSS) vulnerability in tinacms (npm), affecting versions < 3.9.3. It is fixed in 3.9.3, 2.1.7.
TinaCMS 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. Fixed in https://github.com/tinacms/tinacms/pull/7056 via a sanitizeUrl() helper (case-insensitive, whitespace/control-character-normalized scheme allow-list) applied recursively to Slate trees at parse time and in the default rich-text rendering.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
npm
tinacms (< 3.9.3)@tinacms/mdx (< 2.1.7)tinacms → 3.9.3 (npm)@tinacms/mdx → 2.1.7 (npm)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-55661 is reachable in your applications. Explore open-source security for your team.
See if CVE-2026-55661 is reachable in your applications. Get a demo
Upgrade the following packages to resolve this vulnerability:
tinacms to 3.9.3 or later@tinacms/mdx to 2.1.7 or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-55661 is a medium-severity cross-site scripting (XSS) vulnerability in tinacms (npm), affecting versions < 3.9.3. It is fixed in 3.9.3, 2.1.7. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
tinacms (npm) (versions < 3.9.3)@tinacms/mdx (npm) (versions < 2.1.7)Yes. CVE-2026-55661 is fixed in 3.9.3, 2.1.7. Upgrade to this version or later.
Whether CVE-2026-55661 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
tinacms to 3.9.3 or later@tinacms/mdx to 2.1.7 or later