CVE-2026-72794 is a high-severity (CVSS 8.6) CWE-522 vulnerability in github.com/siyuan-note/siyuan/kernel. O3 Security confirms whether CVE-2026-72794 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
SiYuan: The session-cookie signing key (Conf.CookieKey) is returned to anonymous readers by /api/system/getConf
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-72794.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-72794 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 369,023 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/siyuan-note/siyuan/kernelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
CVE: This vulnerability corresponds to CVE-2026-72794.
Summary
/api/system/getConf returns Conf.CookieKey, the key used to sign the server's session cookies in its response body. The endpoint is registered with CheckAuth only, so the field reaches the publish RoleReader token and the anonymous account when Publish.Auth.Enable is false.
The configuration-export endpoint in the same file strips this exact field before returning config, so the project already treats it as secret. The reader-facing masking path does not.
Details
| Item | Detail |
|---|---|
| Route | kernel/api/router.go:70 POST /api/system/getConf → model.CheckAuth → getConf |
| Middleware | CheckAuth only — no CheckReadonly, no CheckAdminRole |
| Leaked field | AppConf.CookieKey, serialized as cookieKey |
| Purpose of the field | Signing key for the siyuan session cookie |
The field survives every stage of the masking chain. getConf masks through GetMaskedConf() → HideConfSecret() (non-administrators) → FilterConfByPublishIgnore() (readers) → the browser-side System-path strip. CookieKey is removed by none of them:
GetMaskedConfmasksUserData,MCPOAuthandAccessAuthCodeonly.HideConfSecretnullsAI,Api,Flashcard,ServerAddrs,Publish,Repo,Sync,Secrets,Variablesand the System paths. It contains no reference toCookieKey.FilterConfByPublishIgnoretouchesUILayoutonly.- The browser-side strip removes System paths only.
The key is live, not vestigial. It is passed straight into the session store at startup:
cli/cmd/serve.go:67 go server.Serve(false, model.Conf.CookieKey)
kernel/server/serve.go:152 sessionStore = cookie.NewStore([]byte(cookieKey))
kernel/server/serve.go:159 ginServer.Use(sessions.Sessions("siyuan", sessionStore))
gin-contrib/sessions/cookie.NewStore constructed with a single key uses that key as the gorilla/securecookie HMAC key. The siyuan session cookie is therefore signed with the value the endpoint hands out. An attacker holding it can mint and modify session cookies that the server accepts as authentic.
Guarded sibling, in the same file. exportConf (kernel/api/system.go:299) clones the configuration before returning it and explicitly clears both secrets:
kernel/api/system.go:360 clonedConf.CookieKey = ""
clonedConf.NotebookCrypto = nil
The project has already classified CookieKey as a value that must not leave the server. The getConf masking path omits the same field.
Ceiling is environment-dependent, floor is not. Escalating a forged session to administrator additionally requires the forged SessionData to carry the matching AccessAuthCode, which GetMaskedConf does mask or the instance to have no access-auth code configured, which is a common deployment. The unconditional impact, present on every instance, is the disclosure of a persistent cryptographic secret to an unauthenticated party together with the cookie-forgery capability that follows from it. Rotating the key invalidates all existing sessions, so this is not a secret that can be quietly refreshed.
Proof of Concept
Precondition: publish mode enabled (default port 6808); anonymous when Publish.Auth.Enable is false, otherwise any publish reader account.
POST http://127.0.0.1:6808/api/system/getConf
{}
→ 200
The response body's conf object contains a cookieKey field holding the
server's session-signing key in cleartext.
Differential check against the endpoint that does strip it:
POST http://127.0.0.1:6808/api/system/exportConf
→ cookieKey is empty, notebookCrypto is null
The same value is withheld by one endpoint and returned by the other.
Impact
An anonymous reader in publish mode or any publish RoleReader obtains the server's session-cookie signing key. This is a persistent cryptographic secret whose disclosure cannot be remediated without invalidating every active session. Possession of the key permits forging and tampering with siyuan session cookies that the server will validate as authentic. On instances with no access-auth code configured, or where a forged session's contents otherwise satisfy the server's checks, this extends to authenticating as a privileged user.
Suggested fix
Clear CookieKey in HideConfSecret for all non-administrator responses. The more durable fix is to route non-administrator getConf through the exportConf cloner, which already handles CookieKey, NotebookCrypto, Account, Stat, System.ID, Export.PandocBin and the AI keys replacing the current blocklist, which fails open on every field nobody thought to add, with the allowlist-style cloner the project already maintains.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/siyuan-note/siyuan/kernel | all versions | 0.0.0-20260725123945-77421530be4a |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/siyuan-note/siyuan/kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/siyuan-note/siyuan/kernel to 0.0.0-20260725123945-77421530be4a or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-72794 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-72794 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-72794. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-72794 in your dependencies?
O3 detects CVE-2026-72794 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.