Summary
SiYuan: Missing publish-access filter on getBlockAttrs and batchGetBlockAttrs discloses block attributes (name, alias, memo, custom fields) of protected documents
CVE: This vulnerability corresponds to CVE-2026-72803.
POST /api/attr/getBlockAttrs and POST /api/attr/batchGetBlockAttrs return a block's full attribute set (IAL) with no publish-access check. Both are CheckAuth-only, so they are reachable by the publish RoleReader token and by the anonymous account when Publish.Auth.Enable is false. An anonymous reader supplying a block ID receives the block's name, alias, memo, bookmark, tags, and every custom-* attribute including for blocks in publish-forbidden and password-protected documents. The batch variant accepts an ID list, making it a bulk extraction primitive.
Details
Neither handler applies a filter:
// /api/attr/getBlockAttrs (router line 301)
ret.Data = sql.GetBlockAttrs(id)
// /api/attr/batchGetBlockAttrs (router line 302)
ret.Data = sql.BatchGetBlockAttrs(idList)
sql.GetBlockAttrs is a direct database read returning the block's entire IAL: name, alias, memo, bookmark, tags, and any custom-* key/value the user has set. Several of these are user-authored free text memos in particular are freeform notes attached to a block so this is document content, not merely structural metadata.
batchGetBlockAttrs takes an arbitrary list of block IDs in a single request, so an attacker holding a set of block IDs can sweep attributes across the entire workspace in one call.
Guarded-sibling asymmetry. The sibling metadata endpoint getBlockInfo calls checkBlockPublishAccess(c, id, ret) before returning; getBlockAttrs and batchGetBlockAttrs call nothing.
Verified at origin/master: both handler bodies contain no publish-access, publish-ignore, or readonly-role check, and both routes are registered CheckAuth without CheckAdminRole.
Proof of Concept
Precondition: publish mode enabled (default port 6808); anonymous when Publish.Auth.Enable is false, otherwise any publish reader account. A document is marked publish-forbidden (or password-protected) and contains a block with a memo and a custom attribute set.
Single-block disclosure:
POST http://127.0.0.1:6808/api/attr/getBlockAttrs
{"id":"<BLOCK_ID_IN_PROTECTED_DOC>"}
Returns the block's IAL: name, alias, memo, bookmark, tags, and all custom-* values.
Bulk disclosure:
POST http://127.0.0.1:6808/api/attr/batchGetBlockAttrs
{"ids":["<ID1>","<ID2>","<ID3>"]}
Returns the attribute sets for every supplied ID in one response, with no per-ID authorization.
Control: the sibling getBlockInfo with the same block ID is refused by checkBlockPublishAccess, confirming the boundary is enforced elsewhere and omitted here.
Impact
An anonymous reader (publish mode with auth disabled) or any publish RoleReader can read block attributes belonging to publish-forbidden and password-protected documents, including user-authored memos and arbitrary custom-* values. The batch endpoint turns this into a bulk primitive: given a set of block IDs, an attacker retrieves attributes across the whole workspace in a single request. Confidentiality-only.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
CVE-2026-72803 has a CVSS score of 5.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20260724093256-229fdffd7e4a); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Call checkBlockPublishAccess in getBlockAttrs before returning, matching getBlockInfo. For batchGetBlockAttrs, apply the check per ID and drop unauthorized entries from the response rather than failing the whole batch.
Frequently Asked Questions
- What is CVE-2026-72803? CVE-2026-72803 is a medium-severity missing authorization vulnerability in github.com/siyuan-note/siyuan/kernel (go), affecting versions < 0.0.0-20260724093256-229fdffd7e4a. It is fixed in 0.0.0-20260724093256-229fdffd7e4a. The application does not perform an authorization check before performing a sensitive operation.
- How severe is CVE-2026-72803? CVE-2026-72803 has a CVSS score of 5.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/siyuan-note/siyuan/kernel are affected by CVE-2026-72803? github.com/siyuan-note/siyuan/kernel (go) versions < 0.0.0-20260724093256-229fdffd7e4a is affected.
- Is there a fix for CVE-2026-72803? Yes. CVE-2026-72803 is fixed in 0.0.0-20260724093256-229fdffd7e4a. Upgrade to this version or later.
- Is CVE-2026-72803 exploitable, and should I be worried? Whether CVE-2026-72803 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-72803 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-72803? Upgrade
github.com/siyuan-note/siyuan/kernelto 0.0.0-20260724093256-229fdffd7e4a or later.