Description

Miniflux is a feed reader. 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. A patch is available in version 2.0.43. As a workaround sisable image proxy; default value is `http-only`.

Severity

 

CVSS Version 3.x CVSS Version 2.0

CVSS 3.x Severity and Metrics:

NIST: NVD

Base Score:  N/A

NVD score not yet provided.

CNA:  GitHub, Inc.

Base Score:  4.8 MEDIUM

Vector:  CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings. A CNA provided score within the CVE List has been displayed.

CVSS 2.0 Severity and Metrics:

NIST: NVD

Base Score: N/A

NVD score not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

References to Advisories, Solutions, and Tools

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Hyperlink	Resource
https://github.com/miniflux/v2/blob/b2fd84e0d376a3af6329b9bb2e772ce38a25c31c/ui/proxy.go#L76
https://github.com/miniflux/v2/blob/b2fd84e0d376a3af6329b9bb2e772ce38a25c31c/ui/proxy.go#L90
https://github.com/miniflux/v2/pull/1746
https://github.com/miniflux/v2/releases/tag/2.0.25
https://github.com/miniflux/v2/releases/tag/2.0.43
https://github.com/miniflux/v2/security/advisories/GHSA-mqqg-xjhj-wfgw
https://miniflux.app/docs/configuration.html#proxy-images

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')	GitHub, Inc.

Change History

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