GHSA-3cm4-ccvw-6xr6: SiYuan: history/repo-diff routes skip secret-file guard

### Summary `GHSA-c8r8-95hg-mp34` added a centralized guard, `util.IsForbiddenAbsPath()`, specifically to block access to a small set of sensitive files: `conf/conf.json` (plaintext `accessAuthCode`/API token/cookie key), `data/snippets/conf.json`, the entire `data/templates/` directory, and `data/.siyuan/publishAccess.json` (plaintext publish-mode passwords). It was applied to `kernel/api/file.go` and `kernel/mcp/tools/file.go`. Two other routes in the same server that serve arbitrary files by path, `/history/*path` and `/repo/diff/*path`, construct their target paths independently and were not updated to call this new guard. Since the repo/history snapshot system's tracked root is `data/` (confirmed by `getSyncIgnoreLines()`, whose ignore file lives at `data/.siyuan/syncignore` with entries relative to `data/`), both `data/.siyuan/publishAccess.json` and `data/templates/*` fall within the scope that can legitimately be captured in historical snapshots, meaning a prior version of either file can exist in `util.HistoryDir`/the repo-diff temp checkout even after the live file has been protected by the new guard. This is CWE-862 (Missing Authorization) applied to a very recently introduced protection mechanism. ### Details `kernel/server/serve.go`, `/history/*path` (around line 994): ```go ginServer.GET("/history/*path", model.CheckAuth, model.CheckAdminRole, func(context *gin.Context) { p := filepath.Join(util.HistoryDir, context.Param("path")) // 加密笔记本的历史是密文（.sy/assets/AV），需先解密再输出 if serveEncryptedHistory(context, p) { return } secureAssetContentHeaders(context, p, p) http.ServeFile(context.Writer, context.Request, p) }) ``` No call to `util.IsForbiddenAbsPath(p)` anywhere in this handler. `kernel/server/serve.go`, `/repo/diff/*path` (around line 1241): ```go ginServer.GET("/repo/diff/*path", model.CheckAuth, model.CheckAdminRole, func(context *gin.Context) { requestPath := filepath.Clean(context.Param("path")) if strings.Contains(requestPath, "..") { context.Status(http.StatusUnauthorized) return } ... p := filepath.Join(repoDiffBaseDir, requestPath) if !gulu.File.IsSubPath(repoDiffBaseDir, p) { context.Status(http.StatusUnauthorized) return } http.ServeFile(context.Writer, context.Request, p) }) ``` This route does have its own traversal protection (`..` rejection and `IsSubPath` containment within `repoDiffBaseDir`), but that only prevents escaping the diff-checkout directory, it does nothing to prevent retrieving a *legitimately checked-out historical copy* of `publishAccess.json` or a templates file from within that directory, which is exactly what the new guard exists to prevent regardless of which directory the copy currently sits in. `util.IsForbiddenAbsPath()` itself (`kernel/util/path_guard.go`, introduced by the referenced fix) confirms the intended scope: ```go // 禁止访问 data/.siyuan/publishAccess.json（含发布模式明文访问密码） publishAccessPath := NormalizeAndResolve(filepath.Join(DataDir, ".siyuan", "publishAccess.json")) if fileNorm == publishAccessPath { return true } ``` and ```go // 禁止访问 data/templates 目录（含目录本身及其全部子路径） templatesBase := NormalizeAndResolve(filepath.Join(DataDir, "templates")) if fileNorm == templatesBase || gulu.File.IsSubPath(templatesBase, fileNorm) { return true } ``` Both are paths within `data/`, the same root the sync/history/repo system tracks. ### Step-by-step reproduction 1. As the workspace admin, enable Publish with a password on at least one notebook (creating `data/.siyuan/publishAccess.json` with a plaintext password), then let a sync/backup snapshot capture this state (or check whether local history capture already covers `data/.siyuan/` in the deployed version). 2. Change or remove the publish password, so the live `publishAccess.json` no longer contains the old plaintext password the new guard is meant to hide, going forward. 3. As the admin, request the historical/diff version instead of the live file: ```bash curl -s http://<target>:6806/history/<snapshot-path-to-publishAccess.json> \ -u "<workspaceName>:<accessAuthCode>" curl -s http://<target>:6806/repo/diff/<diff-path-to-publishAccess.json> \ -u "<workspaceName>:<accessAuthCode>" ``` 4. Expected if consistently protected, matching the behavior the new guard already provides on the live-file endpoints: rejected. Observed: neither handler calls `IsForbiddenAbsPath`, so the historical copy is served if it exists in that location. *(Not run against a live compiled kernel, same sandbox limitation noted throughout this review; both handlers are read directly from source at the reviewed commit, and `IsForbiddenAbsPath`'s scope, plus the sync-root confirmation via `getSyncIgnoreLines()`, are quoted directly above. Whether these specific files are captured by history/repo snapshots in a given deployment depends on the workspace's actual usage history and was not independently verified against a live instance in this review.)* ### Impact An admin-authenticated request to either route can potentially retrieve a historical copy of `data/.siyuan/publishAccess.json` (disclosing a plaintext publish-mode password even after it has been changed or the live file has been protected) or a `data/templates/*` file, directly undermining the protection `GHSA-c8r8-95hg-mp34` was written four days prior to this review specifically to provide, via two routes that predate that fix and were not updated alongside it. ``` ## Affected products | Field | Value | |---|---| | Ecosystem | **Go** | | Package name | `github.com/siyuan-note/siyuan/kernel` | | Affected versions | Present as of commit `251596f` (2026-08-12, the version this review confirmed), i.e. postdates and was not covered by the `GHSA-c8r8-95hg-mp34` fix (commit `3542530`, 2026-08-08) | | Patched versions | *(none yet, leave blank until a fix is released)* | ## Severity | Field | Value | |---|---| | Vector string | `CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:M/I:N/A:N` | | Score | **~5.9 (Medium)**, `PR:H` since admin authentication is required at the HTTP layer, confidentiality impact scoped to whatever sensitive historical content happens to exist in the tracked snapshots for a given deployment (a real but deployment-dependent condition, honestly reflected as Medium rather than assumed to always be present), no integrity/availability impact since both are read-only. | ## Weaknesses (CWE) - **CWE-862**: Missing Authorization (primary) - **CWE-200**: Exposure of Sensitive Information to an Unauthorized Actor ## Notes for filing - Direct, narrow follow-up to `GHSA-c8r8-95hg-mp34`; recommend referencing that advisory directly when filing, since this is precisely the "sibling caller missed" pattern that fix's own centralization (moving the check into a shared `util` function) was presumably intended to prevent, just for two callers that existed before the shared function did and weren't migrated to it. - Suggested fix: add `if util.IsForbiddenAbsPath(p) { ... reject ... }` to both handlers, matching the pattern already applied in `kernel/api/file.go` and `kernel/mcp/tools/file.go`.

An attacker who has obtained or phished the workspace admin accessAuthCode, or a malicious insider with admin rights, sends authenticated GET requests to /history/<snapshot>/.siyuan/publishAccess.json or to /repo/diff/ for a historical checkout. The server returns the old plaintext publish password even though the live file is now blocked by IsForbiddenAbsPath(). The attacker uses the recovered password to access protected published notebooks, which may hold sensitive internal documentation or AI knowledge-base content. Credential reuse across other systems can widen the impact.