High [CVE-2026-58253] Authentication bypass and privilege escalation via parser fast path
This high-severity Red Hat Linux advisory covers CVE-2026-58253.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system.
Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges associated with that connection type.
This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16. A flaw was found in NATS Server.
This allows an unauthenticated attacker on an adjacent network to bypass inter-server authentication. Consequently, the attacker can operate with the privileges of a trusted connection, leading to a high impact on data integrity.
Red Hat severity: Important — CVSS 8.8 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L). Weakness: CWE-551.
Red Hat lists Red Hat Hardened Images as not affected.
Is CVE-2026-58253 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-58253 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-58253?
Upgrade to a fixed release named by Red Hat:
- 2.14.0
- 2.12.7
- 2.11.16
Confirm against the vendor advisory before you patch.
- < 2.14.0
- < 2.12.7
- < 2.11.16
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
- 2.14.0
- 2.12.7
- 2.11.16
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Mitigation checklist
- To mitigate this issue, avoid enabling the `no_auth_user` configuration in NATS Server. If `no_auth_user` is required, restrict network access to NATS route and leafnode listeners using firewall rules to only trusted hosts and networks. This limits the attack surface by preventing unauthenticated access from adjacent networks. A restart of the NATS server may be required for configuration changes to take effect.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Get an email when Red Hat publishes the next one.
See Red Hat's last 90 days of advisories first. Then choose one product with live alerts free for life, or a free month of real-time alerts on everything with the severity, the fixed version and the vendor's link (card needed, then US$15/month; we email you before the first charge).
More Red Hat Linux advisories
- CVE-2026-119977Oct 31, 2026Arbitrary code execution via predictable upgrade staging paths
- CVE-2026-111497Oct 22, 2026Out-of-Bounds Write in Google Brotli Decoder
- CVE-2026-109619Oct 21, 2026fatal error handling retains stale request state leading to use-after-free
- CVE-2026-109618Oct 21, 2026OOM bailout during request parsing leads to memory corruption and RCE
- CVE-2026-97229Oct 13, 2026integer overflow issue in CI/CD regular expression compiler
- CVE-2026-64849Aug 17, 2026Unauthenticated full-read SSRF in webhook delivery: _validate_webhook_url bypassed
iPhone and Android apps · New on the App Store
Monitor future Red Hat Linux CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 34 official vendor sources and 160+ reviewed platform categories.
Discussion(0)
No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.
Sign in to join the discussion.