CVE-2026-45739

Strawberry's bundled GraphiQL template wrote values from the GraphiQL headers editor into the browser URL query string. If a user entered a sensitive header, such as Authorization: Bearer <token>, the value could become visible in browser history, copied links, and server/proxy/CDN access logs after a page reload or shared request.

Affected Versions

• Affected: strawberry-graphql >= 0.288.4, <= 0.315.3
• Patched: 0.315.4

The vulnerable behavior was introduced by the GraphiQL URL-sharing implementation in commit 9315ef80, first included in release 0.288.4.

Technical Details

The bundled strawberry/static/graphiql.html template parsed URL query parameters into a parameters object and used those values to initialize GraphiQL state. It also updated the URL on editor changes using history.replaceState.

Before the fix, header values were handled like shareable query text and variables:

const [headers, setHeaders] = React.useState(parameters.headers);

function onEditHeaders(newHeaders) {
  setHeaders(newHeaders);
  updateURL({ headers: newHeaders });
}

This meant arbitrary header text entered into the IDE could be serialized into ?headers=....

Workarounds

Until a patched version can be used, applications can mitigate this issue by disabling the bundled IDE in production:

GraphQLRouter(schema, graphql_ide=None)

Equivalent graphql_ide=None configuration is available in Strawberry's other HTTP integrations.

Applications can also provide a custom GraphiQL template that does not serialize header values into the URL.

Credits

Reported by @lpschroer.

Applications that expose Strawberry's default GraphiQL IDE may leak sensitive HTTP header values entered by users into the GraphiQL headers editor. The default IDE is enabled by graphql_ide="graphiql" across Strawberry HTTP integrations unless disabled or replaced by the application.

The exposure is limited to the browser-based IDE. GraphQL query execution is not affected, and this issue does not allow an attacker to directly execute operations or bypass authorization. Practical exploitation requires a user to enter a secret into the GraphiQL headers editor and then expose the resulting URL, for example by refreshing the page, copying the URL, sharing the URL, or causing the URL to be recorded by logging infrastructure.

CVE-2026-45739 has a CVSS score of 3.1 (Low). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.315.4); upgrading removes the vulnerable code path.

Kodem intelligence

The GraphiQL template no longer calls updateURL from onEditHeaders. Query and variable URL sharing remain unchanged, and existing URLs with headers=... can still initialize the headers editor. Header persistence via GraphiQL's own shouldPersistHeaders: true behavior remains enabled, so newly edited headers can still persist locally without being placed in the URL.

1. What is CVE-2026-45739? CVE-2026-45739 is a low-severity security vulnerability in strawberry-graphql (pip), affecting versions >= 0.288.4, <= 0.315.3. It is fixed in 0.315.4.
2. How severe is CVE-2026-45739? CVE-2026-45739 has a CVSS score of 3.1 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of strawberry-graphql are affected by CVE-2026-45739? strawberry-graphql (pip) versions >= 0.288.4, <= 0.315.3 is affected.
4. Is there a fix for CVE-2026-45739? Yes. CVE-2026-45739 is fixed in 0.315.4. Upgrade to this version or later.
5. Is CVE-2026-45739 exploitable, and should I be worried? Whether CVE-2026-45739 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
6. What actually determines whether CVE-2026-45739 is exploitable, and how bad it is? 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.
7. How do I fix CVE-2026-45739? Upgrade strawberry-graphql to 0.315.4 or later.