CVE-2026-27889

EUVD-2026-15962
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server.  This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 44.62%
Affected Products (NVD)
VendorProductVersion
linuxfoundationnats-server
2.2.0 ≤
𝑥
< 2.11.14
linuxfoundationnats-server
2.12.0 ≤
𝑥
< 2.12.5
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
Red HatMulticluster Global Hub 1.5.4
1778867753 ≤
𝑥
< *
ADP
Red HatRed Hat multicluster global hub 1.4.4
1779579439 ≤
𝑥
< *
ADP
Red HatRed Hat multicluster global hub 1.6.0
1780167118 ≤
𝑥
< *
ADP
Debian logo
Debian Releases
Debian Product
Codename
nats-server
bookworm
vulnerable
forky
2.14.3-1
fixed
sid
2.14.3-1
fixed
trixie
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
nats-server
jammy
dne
noble
needs-triage
questing
ignored
resolute
needs-triage