CVE-2026-74904 — kernel

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:

The clearest, most severe example, getRefText (POST /api/block/getRefText, kernel/api/router.go:238):

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

# 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.