{"schema_version":"1.7.3","id":"GHSA-xwh2-742g-w3wp","published":"2026-01-07T19:22:14Z","modified":"2026-02-03T03:15:42.309795Z","aliases":["CVE-2026-21885","GO-2026-4287"],"summary":"Miniflux Media Proxy SSRF via /proxy endpoint allows access to internal network resources","details":"### Summary\nMiniflux'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.\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   - `<img src=\"http://<internal-target>/secret\">`\n   (Note: `<internal-target>` 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/<encodedDigest>/<encodedURL>`) 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","affected":[{"package":{"name":"miniflux.app/v2","ecosystem":"Go","purl":"pkg:golang/miniflux.app/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.2.16"}]}],"database_specific":{"last_known_affected_version_range":"<= 2.2.15","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/01/GHSA-xwh2-742g-w3wp/GHSA-xwh2-742g-w3wp.json"}}],"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"}],"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"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"}]}