NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217)
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protocol metadata for sessions in the account. This issue is fixed in versions 2.14.3 and 2.12.12.
BIT-nats-2026-58214
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:BIT-nats-2026-58214
nats
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 2.12.12
Source reference:
/affected/0/ranges2.14.3Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.12.12"
},
{
"introduced": "2.14.0"
},
{
"fixed": "2.14.3"
}
]
}
],
"package": {
"name": "nats",
"purl": "pkg:bitnami/nats",
"ecosystem": "Bitnami"
},
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
}
],
"database_specific": {
"source": "https://github.com/bitnami/vulndb/tree/main/data/nats/BIT-nats-2026-58214.json"
}
}
]- Related CVEs
- CVE-2026-58214
Source reference:
/aliases
Publisher severity
medium
Source reference: /database_specific/severity
- Event
- #25945 · Revision 1
- Added to Heist Feed
- Publisher date