GHSA-44XR-MRHH-QM78

Vulnerability from github – Published: 2026-10-15 20:12 – Updated: 2026-10-15 20:12
VLAI
Summary
Nginx UI: Casdoor SSO callback uses a constant `state` parameter (login CSRF)
Details

Summary

In 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.

Details

api/user/casdoor.go:92-117 (GetCasdoorUri):

func GetCasdoorUri(c *gin.Context) {
    clientId := settings.CasdoorSettings.ClientId
    redirectUri := settings.CasdoorSettings.RedirectUri
    state := settings.CasdoorSettings.Application      // ← constant
    ...
    c.JSON(http.StatusOK, gin.H{
        "uri": fmt.Sprintf(
            "%s/login/oauth/authorize?client_id=%s&response_type=code&redirect_uri=%s&state=%s&scope=read",
            endpoint, clientId, encodedRedirectUri, state),
    })
}

api/user/casdoor.go:24-90 (CasdoorCallback):

type CasdoorLoginUser struct {
    Code  string `json:"code" binding:"required,max=255"`
    State string `json:"state" binding:"required,max=255"`
}

func CasdoorCallback(c *gin.Context) {
    var loginUser CasdoorLoginUser
    if !cosy.BindAndValid(c, &loginUser) { return }
    ...
    // state is NEVER compared to a per-session value
    token, err := casdoorsdk.GetOAuthToken(loginUser.Code, loginUser.State)
    ...
    u, err := user.GetUser(claims.Name)        // username from Casdoor's JWT
    ...
    userToken, err := user.GenerateJWT(u)       // JWT minted for whatever user came back
}

Compare 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.

Proof of Concept

  1. Attacker initiates a Casdoor authorisation flow on their own browser, obtaining an authorisation code for their Casdoor account.
  2. Attacker hosts a page that auto-submits the captured code to the victim's nginx-ui:

```html
document.getElementById('x').submit()

```

  1. 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.
  2. Victim, believing they are using their own account, configures sites / TLS keys; the attacker reads them.

Impact

Login 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.

Patches

Mirror the OIDC implementation:

+ import (
+    "crypto/rand"
+    "crypto/subtle"
+    "encoding/hex"
+    ...
+ )

 func GetCasdoorUri(c *gin.Context) {
     ...
-    state := settings.CasdoorSettings.Application
+    b := make([]byte, 16)
+    if _, err := rand.Read(b); err != nil {
+        cosy.ErrHandler(c, err); return
+    }
+    state := hex.EncodeToString(b)
+    c.SetSameSite(http.SameSiteLaxMode)
+    c.SetCookie("casdoor_state", state, 600, "/", "",
+                cSettings.ServerSettings.EnableHTTPS, true)
     ...
 }

 func CasdoorCallback(c *gin.Context) {
+    expected, err := c.Cookie("casdoor_state")
+    if err != nil {
+        c.AbortWithStatusJSON(http.StatusBadRequest,
+            gin.H{"message":"missing state cookie"}); return
+    }
     var loginUser CasdoorLoginUser
     if !cosy.BindAndValid(c, &loginUser) { return }
+    if subtle.ConstantTimeCompare([]byte(expected), []byte(loginUser.State)) != 1 {
+        c.AbortWithStatusJSON(http.StatusBadRequest,
+            gin.H{"message":"invalid state"}); return
+    }
     ...
 }

Workarounds

Disable Casdoor SSO until patched. The OIDC integration in api/user/oidc.go is correctly implemented and can be used as a substitute.

References

Credits

Vishal Shukla (@shukla304) and Sechub.dev AI Agent.

Severity
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 1.9.10-0.20260703131214-23d1934099b0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "Nginx-UI"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-84312"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-287",
      "CWE-352"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-15T20:12:52Z",
    "nvd_published_at": "2026-10-12T22:17:05Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nIn the Casdoor SSO flow, the OAuth `state` parameter is hard-coded to `settings.CasdoorSettings.Application` \u2014 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\u0027s 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      // \u2190 constant\n    ...\n    c.JSON(http.StatusOK, gin.H{\n        \"uri\": fmt.Sprintf(\n            \"%s/login/oauth/authorize?client_id=%s\u0026response_type=code\u0026redirect_uri=%s\u0026state=%s\u0026scope=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, \u0026loginUser) { 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\u0027s 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\u0027s nginx-ui:\n\n   ```html\n   \u003chtml\u003e\u003cbody\u003e\u003cform action=\"https://victim.example/api/casdoor_callback\" method=\"POST\"\n                     enctype=\"text/plain\" id=\"x\"\u003e\n     \u003cinput name=\u0027{\"code\":\"\u003cattacker_code\u003e\",\"state\":\"\u003cApp\u003e\",\"junk\":\"\u0027 value=\u0027\"}\u0027\u003e\n   \u003c/form\u003e\n   \u003cscript\u003edocument.getElementById(\u0027x\u0027).submit()\u003c/script\u003e\n   \u003c/body\u003e\u003c/html\u003e\n   ```\n\n3. Server exchanges the attacker\u0027s `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`) \u2014 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 \u2014 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 \u2014 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, \u0026loginUser) { 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.",
  "id": "GHSA-44xr-mrhh-qm78",
  "modified": "2026-10-15T20:12:52Z",
  "published": "2026-10-15T20:12:52Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-44xr-mrhh-qm78"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84312"
    },
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/0xJacky/nginx-ui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Nginx UI: Casdoor SSO callback uses a constant `state` parameter (login CSRF)"
}



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