GHSA-5GQC-QHRJ-9XW8
Vulnerability from github – Published: 2026-04-14 23:15 – Updated: 2026-04-24 20:39Summary
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": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.16.1"
},
"package": {
"ecosystem": "Go",
"name": "github.com/oxia-db/oxia"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.16.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-40943"
],
"database_specific": {
"cwe_ids": [
"CWE-362"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-14T23:15:00Z",
"nvd_published_at": "2026-04-21T22:16:19Z",
"severity": "HIGH"
},
"details": "### Summary\nA 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`).\n\n### Impact\nA 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.\n\nAll versions are affected.\n\n### Details\nIn `oxiad/dataserver/controller/lead/session.go`, the `heartbeat()` method performs a blocking `s.heartbeatCh \u003c- 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 \u2014 a deadlock.\n\nAdditionally, in `session_manager.go`, `KeepAlive()` releases the session manager\u0027s read lock before calling `heartbeat()`, creating a TOCTOU window where the session can be removed and closed between the lookup and the heartbeat call.\n\n### Patches\nFixed 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.\n\n### Workarounds\nNo workaround available.",
"id": "GHSA-5gqc-qhrj-9xw8",
"modified": "2026-04-24T20:39:44Z",
"published": "2026-04-14T23:15:00Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/oxia-db/oxia/security/advisories/GHSA-5gqc-qhrj-9xw8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40943"
},
{
"type": "PACKAGE",
"url": "https://github.com/oxia-db/oxia"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Oxia affected by server crash via race condition in session heartbeat handling"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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