CVE-2026-29785

Summary

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.14 and 2.12.5, if the nats-server has the "leafnode" configuration enabled (not default), then anyone who can connect can crash the nats-server by triggering a panic. This happens pre-authentication and requires that compression be enabled (which it is, by default, when leafnodes are used). Versions 2.11.14 and 2.12.5 contain a fix. As a workaround, disable compression on the leafnode port.

Affected Software

Weaknesses

• CWE-476: CWE-476: NULL Pointer Dereference

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

github.com/nats-io/nats-server: NATS-Server: Denial of Service via leafnode compression

Additional References

• https://access.redhat.com/security/cve/CVE-2026-29785
• https://bugzilla.redhat.com/show_bug.cgi?id=2451444
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29785.json
• https://access.redhat.com/errata/RHSA-2026:22347
• https://access.redhat.com/errata/RHSA-2026:21769
• https://access.redhat.com/errata/RHSA-2026:23345

References

• https://github.com/nats-io/nats-server/security/advisories/GHSA-52jh-2xxh-pwh6
• https://github.com/nats-io/nats-server/commit/a1488de6f2ba6e666aef0f9cce0016f7f167d6a8
• https://advisories.nats.io/CVE/secnote-2026-04.txt

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