CVE-2023-27592

Workarounds

• Disable image proxy (default value is http-only).

References

• https://miniflux.app/docs/configuration.html#proxy-images

Since v2.0.25, Miniflux will automatically proxy images served over HTTP to prevent mixed content errors.

When an outbound request made by the Go HTTP client fails, the html.ServerError is returned unescaped without the expected Content Security Policy header added to valid responses.

By creating an RSS feed item with the inline description containing an <img> tag with a srcset attribute pointing to an invalid URL like http:a<script>alert(1)</script>, we can coerce the proxy handler into an error condition where the invalid URL is returned unescaped and in full.

This results in JavaScript execution on the Miniflux instance as soon as the user is convinced (e.g. by a message in the alt text) to open the broken image.

An attacker can execute arbitrary JavaScript in the context of a victim Miniflux user when they open a broken image in a crafted RSS feed. This can be used to perform actions on the Miniflux instance as that user and gain administrative access to the Miniflux instance if it is reachable and the victim is an administrator.

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.

CVE-2023-27592 has a CVSS score of 4.8 (Medium). The vector is network-reachable, low 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 (2.0.43); upgrading removes the vulnerable code path.

Kodem intelligence

PR #1746 fixes the problem. Available in Miniflux >= 2.0.43.

1. What is CVE-2023-27592? CVE-2023-27592 is a medium-severity cross-site scripting (XSS) vulnerability in miniflux.app/v2 (go), affecting versions >= 2.0.25, < 2.0.43. It is fixed in 2.0.43. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2023-27592? CVE-2023-27592 has a CVSS score of 4.8 (Medium). 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 miniflux.app/v2 are affected by CVE-2023-27592? miniflux.app/v2 (go) versions >= 2.0.25, < 2.0.43 is affected.
4. Is there a fix for CVE-2023-27592? Yes. CVE-2023-27592 is fixed in 2.0.43. Upgrade to this version or later.
5. Is CVE-2023-27592 exploitable, and should I be worried? Whether CVE-2023-27592 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-2023-27592 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-2023-27592? Upgrade miniflux.app/v2 to 2.0.43 or later.