CVE-2026-40943 — oxia
CVE-2026-40943 is a CWE-362 vulnerability in github.com/oxia-db/oxia. A fix is available for github.com/oxia-db/oxia — see the affected versions and patch details below.
Oxia: Server crash via race condition in session heartbeat handling
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-40943.
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.
Real-World Exposure
github.com/oxia-db/oxiaReal-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
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/oxia-db/oxia | all versions | 0.16.2go get github.com/oxia-db/oxia@v0.16.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/oxia-db/oxia, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/oxia-db/oxia to 0.16.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40943 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-40943 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-40943. 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-2026-40943 in your dependencies?
O3 Security finds CVE-2026-40943 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.