High severity · published Jul 8, 2026
CVE-2026-58250
NATS Server: Pre-auth server crash via double INFO in leafnode handshake
7.5
CVSS
0.7%
EPSS
No
On KEV
Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.12.8 and 2.11.17, an unauthenticated peer with network access to a leafnode listener with compression enabled could crash the server during the pre-authentication leafnode handshake by sending repeated leafnode INFO protocol messages before authentication and account setup completed. This issue is fixed in versions 2.12.8 and 2.11.17.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 54% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NA
nats-server · nats-io
< 2.11.17; >= 2.12.0-preview.1, < 2.12.8 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-58250
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-58250
Patch
https://github.com/nats-io/nats-server/commit/8dcb26eaea78fdcbe96dbee5986d6019fd5cb94a
Patch
https://github.com/nats-io/nats-server/commit/fc5fe39177533e9dbdd651d2458285bfae1dde27
Release Notes
https://github.com/nats-io/nats-server/releases/tag/v2.11.17
Release Notes
https://github.com/nats-io/nats-server/releases/tag/v2.12.8
Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-3g5q-cfh2-cq67
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