CVE-2026-40943

Description

### Summary A race condition between session heartbeat processing and session closure can cause the server to panic with `send on closed channel`. The `heartbeat()` method uses a blocking channel send while holding a mutex, and under specific timing with concurrent `close()` calls, this can lead to either a deadlock (channel buffer full) or a panic (send on closed channel after TOCTOU gap in `KeepAlive`). ### Impact A remote client can trigger a server crash by sending rapid `KeepAlive` requests while a session is expiring or being closed. This is a denial-of-service vulnerability that crashes the entire data server process. All versions are affected. ### Details In `oxiad/dataserver/controller/lead/session.go`, the `heartbeat()` method performs a blocking `s.heartbeatCh <- true` send. If the channel buffer is full (size 1), this blocks while holding the session mutex, preventing `close()` from acquiring the lock to close the channel — a deadlock. Additionally, in `session_manager.go`, `KeepAlive()` releases the session manager's read lock before calling `heartbeat()`, creating a TOCTOU window where the session can be removed and closed between the lookup and the heartbeat call. ### Patches Fixed by changing `heartbeat()` to use a non-blocking `select` with a `default` case, and by holding the session manager read lock through the entire `KeepAlive()` operation. ### Workarounds No workaround available.

How to fix CVE-2026-40943

To remediate CVE-2026-40943, upgrade the affected package to a fixed version below.

• —upgrade to 0.16.2 or later

Is CVE-2026-40943 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0, < 0.16.2

CVSS scores

References (3)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-40943
• PATCHgithub.com/oxia-db/oxia
• WEBgithub.com/oxia-db/oxia/security/advisories/GHSA-5gqc-qhrj-9xw8