GHSA-XWH2-742G-W3WP
Vulnerability from github – Published: 2026-01-07 19:22 – Updated: 2026-01-08 21:19Summary
Miniflux's media proxy endpoint (GET /proxy/{encodedDigest}/{encodedURL}) can be abused to perform Server-Side Request Forgery (SSRF). An authenticated user can cause Miniflux to generate a signed proxy URL for attacker-chosen media URLs embedded in feed entry content, including internal addresses (e.g., localhost, private RFC1918 ranges, or link-local metadata endpoints). Requesting the resulting /proxy/... URL makes Miniflux fetch and return the internal response.
Details
- Vulnerable route:
GET /proxy/{encodedDigest}/{encodedURL}(accessible without authentication, but requires a server-generated HMAC-signed URL) - Handler:
internal/ui/proxy.go((*handler).mediaProxy) - Trigger: entry content is rewritten to proxy media URLs (e.g.,
mediaproxy.RewriteDocumentWithAbsoluteProxyURL(...)), producing signed/proxy/...URLs. - Root cause: the proxy validates the URL scheme and HMAC signature, but does not restrict target hosts/IPs. As a result, requests to loopback/private/link-local addresses are allowed and fetched by the server.
PoC
1) Run Miniflux 2.2.15 with default configuration (media proxy enabled by default: MEDIA_PROXY_MODE=http-only).
2) Log in with any normal user account.
3) Subscribe to a feed you control that contains an entry with an image URL pointing to an internal address reachable from the Miniflux server, e.g.:
- <img src="http://<internal-target>/secret">
(Note: <internal-target> must be reachable from the Miniflux process/network; in containerized setups, 127.0.0.1 may not refer to the host.)
4) Open the entry and locate the rewritten media proxy URL (/proxy/<encodedDigest>/<encodedURL>) in the rendered HTML/page source.
5) Request the /proxy/... URL.
Expected (vulnerable): Miniflux fetches the internal URL and returns the internal response (SSRF).
Impact
Type: SSRF (Server-Side Request Forgery) via media proxy
Who is impacted: Miniflux instances with media proxy enabled (default configuration typically enables it for HTTP/mixed content handling).
Impact: attackers with a valid Miniflux account can fetch internal resources reachable from the Miniflux server (e.g., localhost services, private network services, and link-local endpoints such as 169.254.169.254), potentially exposing sensitive data.
Suggested CVSS (v3.1)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N (Base 6.5)
If there any questions or issues reproducing this, please contact: jeongwoolee340@gmail.com
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.2.15"
},
"package": {
"ecosystem": "Go",
"name": "miniflux.app/v2"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.2.16"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-21885"
],
"database_specific": {
"cwe_ids": [
"CWE-918"
],
"github_reviewed": true,
"github_reviewed_at": "2026-01-07T19:22:14Z",
"nvd_published_at": "2026-01-08T14:15:57Z",
"severity": "MODERATE"
},
"details": "### Summary\nMiniflux\u0027s media proxy endpoint (`GET /proxy/{encodedDigest}/{encodedURL}`) can be abused to perform Server-Side Request Forgery (SSRF). An authenticated user can cause Miniflux to generate a signed proxy URL for attacker-chosen media URLs embedded in feed entry content, including internal addresses (e.g., localhost, private RFC1918 ranges, or link-local metadata endpoints). Requesting the resulting `/proxy/...` URL makes Miniflux fetch and return the internal response.\n\n### Details\n- **Vulnerable route**: `GET /proxy/{encodedDigest}/{encodedURL}` (accessible without authentication, but requires a server-generated HMAC-signed URL)\n- **Handler**: `internal/ui/proxy.go` (`(*handler).mediaProxy`)\n- **Trigger**: entry content is rewritten to proxy media URLs (e.g., `mediaproxy.RewriteDocumentWithAbsoluteProxyURL(...)`), producing signed `/proxy/...` URLs.\n- **Root cause**: the proxy validates the URL scheme and HMAC signature, but does not restrict target hosts/IPs. As a result, requests to loopback/private/link-local addresses are allowed and fetched by the server.\n\n### PoC\n1) Run Miniflux 2.2.15 with default configuration (media proxy enabled by default: `MEDIA_PROXY_MODE=http-only`).\n\n2) Log in with any normal user account.\n\n3) Subscribe to a feed you control that contains an entry with an image URL pointing to an internal address reachable from the Miniflux server, e.g.:\n - `\u003cimg src=\"http://\u003cinternal-target\u003e/secret\"\u003e`\n (Note: `\u003cinternal-target\u003e` must be reachable *from the Miniflux process/network*; in containerized setups, `127.0.0.1` may not refer to the host.)\n\n4) Open the entry and locate the rewritten media proxy URL (`/proxy/\u003cencodedDigest\u003e/\u003cencodedURL\u003e`) in the rendered HTML/page source.\n\n5) Request the `/proxy/...` URL.\nExpected (vulnerable): Miniflux fetches the internal URL and returns the internal response (SSRF).\n\n### Impact\n**Type**: SSRF (Server-Side Request Forgery) via media proxy \n**Who is impacted**: Miniflux instances with media proxy enabled (default configuration typically enables it for HTTP/mixed content handling). \n**Impact**: attackers with a valid Miniflux account can fetch internal resources reachable from the Miniflux server (e.g., localhost services, private network services, and link-local endpoints such as 169.254.169.254), potentially exposing sensitive data.\n\n### Suggested CVSS (v3.1)\n`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N` (Base 6.5)\n\n\n\n\nIf there any questions or issues reproducing this, please contact: jeongwoolee340@gmail.com",
"id": "GHSA-xwh2-742g-w3wp",
"modified": "2026-01-08T21:19:09Z",
"published": "2026-01-07T19:22:14Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/miniflux/v2/security/advisories/GHSA-xwh2-742g-w3wp"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-21885"
},
{
"type": "PACKAGE",
"url": "https://github.com/miniflux/v2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Miniflux Media Proxy SSRF via /proxy endpoint allows access to internal network resources"
}
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