CVE-2026-72790 — kernel

CVE: This vulnerability corresponds to CVE-2026-72790.

Relationship to GHSA-8x84-r2ff-h8pq (please read first)

getNotebookInfo is named in the earlier advisory GHSA-8x84-r2ff-h8pq, in its remediation section, which asked for reader filtering on both getNotebookConf and getNotebookInfo. Commit 3bc014c7d applied that filtering to getNotebookConf only.

That advisory grouped getNotebookInfo under BoxCrypt, and getNotebookInfo never returns BoxCrypt. Anyone checking the handler for key material would correctly find none and move on. This report corrects that characterisation and states what the handler actually discloses, which is notebook metadata rather than key material. If you would prefer this tracked as a follow-up on the original advisory rather than separately, that is entirely reasonable.

Summary

/api/notebook/getNotebookInfo is registered with CheckAuth only and applies no authorization check of any kind. Given a notebook identifier, it returns that notebook's author-written name, document count, total size and creation and modification timestamps. It does so for every notebook the server has loaded, including notebooks that lsNotebooks deliberately withholds from readers because they are closed or not publish-visible.

Details

The handler. It validates boxID against the ID pattern, calls box := model.Conf.Box(boxID), returns a not-found response if that is nil, and otherwise returns box.GetInfo() unmodified. GetInfo() (kernel/model/box.go:470) walks the notebook's files and returns the metadata listed above. There is no ownership check and no publish-access check anywhere on the path.

The nil branch is also a minor existence oracle: a valid-format identifier that names no loaded notebook is distinguishable from one that does.

Guarded sibling. lsNotebooks, the notebook lister, is also reader-reachable and does filter. For read-only roles it skips any notebook where notebook.Closed holds, and skips any notebook whose publish-access entry has !item.Visible. The codebase therefore intends closed and non-published notebooks to be invisible to readers. getNotebookInfo returns their name and statistics to any reader who supplies the identifier.

Precedent. GHSA-f2rw-w22v-54vh restricted getEncryptedNotebookStatus, which disclosed encrypted-notebook names and lock state, to administrators. getNotebookInfo is the non-encrypted analogue, disclosing regular notebook names and statistics including for notebooks outside the reader's publish scope, and was not restricted.

Reachability, stated precisely, because it differs by branch.

On v3.7.3 a reader can obtain the identifier of a notebook they cannot see, by chaining two endpoints that are currently ungated on that branch. getBlockDefIDsByRefText returns block and document identifiers workspace-wide, including from hidden notebooks. getPathByID then returns the owning notebook identifier for any such block, in its notebook field. getFullHPathByID additionally discloses the notebook name directly. The chain requires no special conditions beyond a reference text that occurs somewhere in the workspace.

On the development branch those sources are already closed. getPathByID now gates through CheckBlockIdMetadataAccessableByPublishAccessInBox, getIDsByHPath through filterFileTreeBlockIDsByPublishDiscoverability, and getBlockDefIDsByRefText and getFullHPathByID are likewise gated. Notebook identifiers are a fourteen-digit timestamp plus seven random characters, and Conf.Box(boxID) returns non-nil only for loaded notebooks, so guessing is not practical. A reader-reachable route on the development branch that yields the identifier of a hidden notebook was not found.

So on the development branch this is defence in depth rather than a live path. It is reported because the handler itself remains unguarded on both branches, and because closing it removes any dependence on those identifier sources staying gated in future.

Proof of Concept

Precondition: publish mode enabled (default port 6808), anonymous when Publish.Auth.Enable is false, otherwise any publish reader account. A notebook that is closed or not publish-visible. Steps 1 and 2 apply to v3.7.3; on the development branch, start at step 3 with a known identifier.

Step 1, obtain block identifiers workspace-wide:

POST http://127.0.0.1:6808/api/block/getBlockDefIDsByRefText
{"anchor":"<a word likely to occur anywhere in the workspace>"}

→ 200, block and document identifiers including ones inside hidden notebooks

Step 2, resolve one to its owning notebook:

POST http://127.0.0.1:6808/api/filetree/getPathByID
{"id":"<identifier from step 1>"}

→ 200, the notebook field carries the hidden notebook's boxID

Step 3, read the notebook's metadata:

POST http://127.0.0.1:6808/api/notebook/getNotebookInfo
{"notebook":"<boxID from step 2>"}

→ 200, returns name, docCount, size, hSize, mtime, ctime, hMtime, hCtime
   for a notebook that lsNotebooks does not return to this same session

The differential is the point: call lsNotebooks with the same session and confirm the notebook is absent from the list, then call getNotebookInfo and receive its name and statistics.

Impact

An anonymous reader in publish mode, or any publish RoleReader, can read the author-written name, document count, total size and activity timestamps of notebooks that are closed or not published, which are exactly the notebooks the notebook lister withholds from them. Notebook names are free text chosen by the author and routinely describe their contents. Document count and size indicate scale, and the modification timestamp reveals recent activity in a workspace area the reader has no access to. Confidentiality only, with no integrity or availability impact, and no document content is disclosed.

Suggested fix

Apply the same filtering lsNotebooks already performs. When IsReadOnlyRoleContext(c) holds, return the not-found response unless the notebook is publish-visible and not closed, before calling GetInfo(). This is the reader filtering the earlier advisory's remediation section requested for this handler.