CVE-2026-74904

Same CWE-862 family, found via an automated bulk sweep of every `/api/block/*` handler in `kernel/api/block.go` for the presence of any access-check reference (`IsReadOnlyRoleContext`, `checkBlockPublishAccess`, `GetPublishAccess`) anywhere in the function body. 17 of 28 candidate endpoints have none. Cross-checked against the file's own sibling functions (`getBlockInfo`, `getBlockDOM`, `getRefIDs`, etc.), which correctly implement the check, confirming this is a real, uneven gap rather than a deliberate design choice for the whole file. ### Summary 17 handlers in `kernel/api/block.go`, all gated only by `model.CheckAuth` with no admin-role requirement, return block content-derived text, structural metadata, or existence information for any block ID supplied, with no access check anywhere in the handler or, for the ones checked in detail, the model functions they call. This is CWE-862 (Missing Authorization), the same class as the companion advisories from this review round, found in a different file via a systematic bulk check rather than manual inspection of each function individually. ### Details Confirmed via automated extraction of every function body between `func NAME(c *gin.Context) {` and the next such declaration, then searching each for any of `IsReadOnlyRoleContext`, `checkBlockPublishAccess`, `GetPublishAccess`, or `PublishAccess`. The following contain none of these, at all: | Endpoint | What it discloses | |---|---| | `getRefText` | The block's actual reference-display text, derived from its content, for any ID (`kernel/api/block.go:564`) | | `getBlockBreadcrumb` | The block's breadcrumb/title path (`:?`) | | `getBlockDefIDsByRefText` | Which block IDs a given reference text resolves to | | `getRefIDsByFileAnnotationID` | Block IDs referencing a given PDF/file annotation | | `getBlockIndex` / `getBlocksIndexes` | A block's position/index within its document | | `getTreeStat` | Structural statistics for a document tree | | `getBlocksWordCount` / `getContentWordCount` | Word/character counts for arbitrary content | | `checkBlockExist` / `checkBlocksExist` | Existence oracle for any block ID | | `getUnfoldedParentID` | The nearest unfolded ancestor of a block | | `checkBlockFold` | Whether a block is currently folded | | `getBlockSiblingID` | A block's sibling in document order | | `getBlockRelevantIDs` | IDs of blocks related to a given block | | `getBlockTreeInfos` | Block tree metadata for a set of IDs | | `checkBlockRef` | Whether a block is referenced elsewhere | The clearest, most severe example, `getRefText` (`POST /api/block/getRefText`, `kernel/api/router.go:238`): ```go func getRefText(c *gin.Context) { ... id := arg["id"].(string) if util.InvalidIDPattern(id, ret) { return } var refText string if notebook, ok := arg["notebook"].(string); ok && notebook != "" && model.IsEncryptedBox(notebook) { refText = model.GetBlockRefTextInBox(id, notebook) } else { refText = model.GetBlockRefText(id) } ... ret.Data = refText } ``` `model.GetBlockRefText(id)` resolves the actual display text used wherever this block is referenced, ordinarily derived from the block's real content, for any `id` in the workspace, with no scoping. For contrast, sibling functions in the same file correctly implement the check, e.g. `getRefIDs` (`kernel/api/router.go:235`) and `getBlockInfo`/`getBlockDOM`/`getBlockKramdown` all contain `if model.IsReadOnlyRoleContext(c) { ... }` guards. This confirms the 17 above are an inconsistency within the file, not an intentional decision that the whole file is exempt from this control. ### Step-by-step reproduction ```bash # id: a block inside a document that was never published, or is # Disable=true in publish access curl -s -X POST http://<target>:6806/api/block/getRefText \ -H "Content-Type: application/json" -d '{"id":"<private-block-id>"}' # Returns the block's actual reference text with no session, no # AccessAuthCode, no publish password. curl -s -X POST http://<target>:6806/api/block/checkBlockExist \ -H "Content-Type: application/json" -d '{"id":"<guessed-block-id>"}' # Confirms or denies existence of any guessed ID workspace-wide. ``` Repeat against any of the other 15 endpoints in the table above, substituting their expected arguments, each returns data with no access check. ### Impact Any published SiYuan workspace discloses block-level content-derived text, structural metadata, and existence information for the *entire* workspace, not just published notebooks, to any anonymous internet visitor. `getRefText` in particular discloses real content text, not just metadata, for any block ID. The existence-oracle endpoints (`checkBlockExist`/`checkBlockRef`) combine with the companion advisory's `getIDsByHPath` title-guessing primitive to let an attacker efficiently probe for and confirm private content without ever needing legitimate access. ``` ## Affected products | Field | Value | |---|---| | Ecosystem | **Go** | | Package name | `github.com/siyuan-note/siyuan/kernel` | | Affected versions | Present at current HEAD (commit `eef1056`/`1673b75`, reviewed 2026-08-03) | | Patched versions | *(none yet, leave blank until a fix is released)* | ## Severity | Field | Value | |---|---| | Vector string | `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N` | | Score | **7.5 (High)**. Network vector, low complexity, no privileges or user interaction required, high confidentiality impact via `getRefText`'s real content-text disclosure plus the combined structural/existence oracle from the other 16, no integrity/availability impact since all 17 are read-only. | ## Weaknesses (CWE) - **CWE-862**: Missing Authorization (primary) - **CWE-204**: Observable Response Discrepancy (contributing, via the existence-oracle endpoints) ## Notes for filing - Same CWE-862 family as the two companion advisories from this review round (asset/attribute-view listing, and path/title resolution). Recommend the maintainers treat all three as one remediation pass: grep every `/api/*` handler for the literal presence of `IsReadOnlyRoleContext` and manually audit every one that lacks it, rather than fixing endpoint-by-endpoint, since the pattern has now recurred across three separate files. - Suggested fix: add `if model.IsReadOnlyRoleContext(c) { ... }` guards matching the pattern already correctly used by this file's own `getBlockInfo`/`getBlockDOM`/`getRefIDs` functions.

No confirmed active exploitation of CVE-2026-74904 has been reported, but organizations should still patch proactively.

Update to patched version: Jupyter Notebook 0.0.0-20260804015139-bd067a4fe9b2.

CVE-2026-74904 has a CVSS v3.1 base score of 7.5 (HIGH). The EPSS exploitation probability is 0.50%.