CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-27889
High (7.5) in linuxfoundation nats-server. EPSS 0.6% chance of exploitation in the next 30 days. Fixed in github.com/nats-io/nats-server/v2 2.11.14, 2.12.5.
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.
Severity
- EPSS
- 0.6% chance of exploitation in the next 30 days; higher than 48% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-190, CWE-1286
- Published
- Modified
- Record from
- the NVD, synced
Affected
- linuxfoundation:nats-server
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-pq2q-rcw4-3hr6 | Go | github.com/nats-io/nats-server/v2 | >=2.2.0 <2.11.14 | 2.11.14 |
| GHSA-pq2q-rcw4-3hr6 | Go | github.com/nats-io/nats-server/v2 | >=2.12.0 <2.12.5 | 2.12.5 |
| GHSA-pq2q-rcw4-3hr6 | Go | github.com/nats-io/nats-server | all versions | no fix published |
| GO-2026-4841 | Go | github.com/nats-io/nats-server | all versions | no fix published |
| GO-2026-4841 | Go | github.com/nats-io/nats-server/v2 | >=2.2.0 <2.11.14 >=2.12.0 <2.12.5 | 2.11.14, 2.12.5 |