{"schema":"threatline.record/2","record":{"id":"CVE-2026-84312","aliases":["GHSA-44xr-mrhh-qm78","GO-2026-6773"],"summary":"Nginx UI: Casdoor SSO callback uses a constant `state` parameter (login CSRF)","details":"## Summary\n\nIn the Casdoor SSO flow, the OAuth `state` parameter is hard-coded to `settings.CasdoorSettings.Application` — a value identical for every user and every login. The callback handler accepts whatever `state` the client sends without comparing it to anything stored in the user agent, enabling a login-CSRF: an attacker can force the victim's browser to authenticate as the *attacker*.\n\n## Details\n\n`api/user/casdoor.go:92-117` (`GetCasdoorUri`):\n\n```go\nfunc GetCasdoorUri(c *gin.Context) {\n    clientId := settings.CasdoorSettings.ClientId\n    redirectUri := settings.CasdoorSettings.RedirectUri\n    state := settings.CasdoorSettings.Application      // ← constant\n    ...\n    c.JSON(http.StatusOK, gin.H{\n        \"uri\": fmt.Sprintf(\n            \"%s/login/oauth/authorize?client_id=%s&response_type=code&redirect_uri=%s&state=%s&scope=read\",\n            endpoint, clientId, encodedRedirectUri, state),\n    })\n}\n```\n\n`api/user/casdoor.go:24-90` (`CasdoorCallback`):\n\n```go\ntype CasdoorLoginUser struct {\n    Code  string `json:\"code\" binding:\"required,max=255\"`\n    State string `json:\"state\" binding:\"required,max=255\"`\n}\n\nfunc CasdoorCallback(c *gin.Context) {\n    var loginUser CasdoorLoginUser\n    if !cosy.BindAndValid(c, &loginUser) { return }\n    ...\n    // state is NEVER compared to a per-session value\n    token, err := casdoorsdk.GetOAuthToken(loginUser.Code, loginUser.State)\n    ...\n    u, err := user.GetUser(claims.Name)        // username from Casdoor's JWT\n    ...\n    userToken, err := user.GenerateJWT(u)       // JWT minted for whatever user came back\n}\n```\n\nCompare with the OIDC implementation in `api/user/oidc.go:35-48`, which generates a random state, stores it in an `oidc_state` cookie, and validates it on the callback. Casdoor has no such check.\n\n## Proof of Concept\n\n1. Attacker initiates a Casdoor authorisation flow on their own browser, obtaining an authorisation `code` for *their* Casdoor account.\n2. Attacker hosts a page that auto-submits the captured `code` to the victim's nginx-ui:\n\n   ```html\n   <html><body><form action=\"https://victim.example/api/casdoor_callback\" method=\"POST\"\n                     enctype=\"text/plain\" id=\"x\">\n     <input name='{\"code\":\"<attacker_code>\",\"state\":\"<App>\",\"junk\":\"' value='\"}'>\n   </form>\n   <script>document.getElementById('x').submit()</script>\n   </body></html>\n   ```\n\n3. Server exchanges the attacker's `code`, looks up the username from `claims.Name` in the local user table, and mints a JWT for *that* row. The callback also sets the `_nginx_ui_secure_session` cookie via `middleware.EnsureSecureSessionCookie(c)` (`casdoor.go:84`) — meaning the victim is now silently authenticated as the attacker.\n4. Victim, believing they are using their own account, configures sites / TLS keys; the attacker reads them.\n\n## Impact\n\nLogin CSRF — the victim is forced to authenticate as the attacker, leading to data exfiltration of anything the victim subsequently uploads or configures. Particularly dangerous when nginx-ui is used by an organisation where Casdoor maps internal identities — the attacker can attribute their changes to the victim.\n\n## Patches\n\nMirror the OIDC implementation:\n\n```diff\n+ import (\n+    \"crypto/rand\"\n+    \"crypto/subtle\"\n+    \"encoding/hex\"\n+    ...\n+ )\n\n func GetCasdoorUri(c *gin.Context) {\n     ...\n-    state := settings.CasdoorSettings.Application\n+    b := make([]byte, 16)\n+    if _, err := rand.Read(b); err != nil {\n+        cosy.ErrHandler(c, err); return\n+    }\n+    state := hex.EncodeToString(b)\n+    c.SetSameSite(http.SameSiteLaxMode)\n+    c.SetCookie(\"casdoor_state\", state, 600, \"/\", \"\",\n+                cSettings.ServerSettings.EnableHTTPS, true)\n     ...\n }\n\n func CasdoorCallback(c *gin.Context) {\n+    expected, err := c.Cookie(\"casdoor_state\")\n+    if err != nil {\n+        c.AbortWithStatusJSON(http.StatusBadRequest,\n+            gin.H{\"message\":\"missing state cookie\"}); return\n+    }\n     var loginUser CasdoorLoginUser\n     if !cosy.BindAndValid(c, &loginUser) { return }\n+    if subtle.ConstantTimeCompare([]byte(expected), []byte(loginUser.State)) != 1 {\n+        c.AbortWithStatusJSON(http.StatusBadRequest,\n+            gin.H{\"message\":\"invalid state\"}); return\n+    }\n     ...\n }\n```\n\n## Workarounds\n\nDisable Casdoor SSO until patched. The OIDC integration in `api/user/oidc.go` is correctly implemented and can be used as a substitute.\n\n## References\n\n* [`api/user/casdoor.go:92-117`](https://github.com/0xJacky/nginx-ui/blob/dev/api/user/casdoor.go#L92-L117)\n* [`api/user/casdoor.go:24-90`](https://github.com/0xJacky/nginx-ui/blob/dev/api/user/casdoor.go#L24-L90)\n* [`api/user/oidc.go:35-48`](https://github.com/0xJacky/nginx-ui/blob/dev/api/user/oidc.go#L35-L48) (correct implementation for comparison)\n\n## Credits\n\nVishal Shukla ([@shukla304](https://github.com/shukla304)) and Sechub.dev AI Agent.","categories":["Web servers"],"product":"Nginx-UI","vendor":"0xJacky","ecosystem":"go","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-44xr-mrhh-qm78","source_modified_at":"2026-10-15T20:12:53Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"go","name":"Nginx-UI"},"range":"< 1.9.10-0.20260703131214-23d1934099b0"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84312","source_modified_at":"2026-10-14T11:36:49.978Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"nginx-ui","vendor":"0xJacky","versions":[{"version":"< 2.4.1","status":"affected"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-44xr-mrhh-qm78","source_modified_at":"2026-10-19T21:40:46.634165616Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"Go","name":"Nginx-UI","purl":"pkg:golang/Nginx-UI"},"ranges":[{"events":[{"introduced":"0"}],"type":"SEMVER"}],"versions":[]}],"fixed_versions":[],"cvss":7.1,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00175,"percentile":0.06619,"score_date":"2026-10-23"},"published_at":"2026-10-12T21:16:56.072Z","modified_at":"2026-10-19T21:40:46.634165616Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-44xr-mrhh-qm78","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-15T20:12:53Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-84312","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-14T11:36:49.978Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-44xr-mrhh-qm78","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-19T21:40:46.634165616Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-84312","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-44xr-mrhh-qm78","tags":["x_refsource_CONFIRM"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84312","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1","tags":["x_refsource_MISC"]},{"url":"https://github.com/advisories/GHSA-44xr-mrhh-qm78","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"poc","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-14T11:34:39.668412Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T21:40:46.634165616Z","content_hash":"4934f6f154356bf1c06184e411f772ab1b84a87c37d0464b3442d1425d5c4665"}}