CVE-2023-27592
Stored XSS in Miniflux when opening a broken image due to unescaped ServerError in proxy handler
Published Mar 17, 2023
CVSS 3.1 · 4.8 Medium
EPSS < 1%
KEV · Not listed
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`.
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`.
Affected Products
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CVE record
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NVD configurations
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Red Hat packages
No data
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OpenCVE enrichment
No data
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| miniflux | v2 | affected |
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No data.
No data available yet.
Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 EUVD |
EUVD-2023-31334 | Stored XSS in Miniflux when opening a broken image due to unescaped ServerError in proxy handler |
 Github GHSA |
GHSA-mqqg-xjhj-wfgw | Stored XSS in Miniflux when opening a broken image due to unescaped ServerError in proxy handler |
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity High
Privileges Required Low
Scope Unchanged
Confidentiality Impact None
Integrity Impact High
Availability Impact None
User Interaction Required
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.586% probability within 30 days)
Exploitation none
Automatable no
Technical Impact partial
References
History
Feb 25, 2025 3:15 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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Subscriptions
Weaknesses
