CVE-2026-82651

### 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`.

SiYuan: /history/*path and /repo/diff/*path potentially exposing historical snapshots of data/.siyuan/publishAccess.json and data/templates/* in github.com/siyuan-note/siyuan/kernel