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Fencer Vulns
medium 4.8

CVE-2023-27592 json

Stored XSS in Miniflux when opening a broken image due to unescaped ServerError in proxy handler

published 2023-03-17 3 y ago modified 2026-09-10 1 mo ago also GHSA-mqqg-xjhj-wfgw , EUVD-2023-31334

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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`.

Patch / fix

  • go miniflux.app/v2 2.0.43
  • miniflux_project miniflux 2.0.43
  • miniflux Alpine 3.17 2.0.43-r0

alpine advisories ALPINE-CVE-2023-27592

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
go miniflux.app/v2
>=2.0.25, <2.0.43
2.0.43

Affected products

  • miniflux v2

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.