NVD / CVE Program· CNA GitHub_M

CVE-2026-58253: NATS Server: Route API Auth Bypass

Noroxi assessment

Priority: Monitor (action score 35/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: azl3 telegraf 1.31.0-23 on Azure Linux 3.0 1.31.0-24.

Low priority for now. Upgrade to azl3 telegraf 1.31.0-23 on Azure Linux 3.0 1.31.0-24 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.8 · v3.1—No exploit Fix available

BDU:2026-09678

Published: Jul 8, 2026
Updated: Oct 25, 2026
EPSS: 0.3% · 30th percentile
CWE: CWE-287

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 35 / 40 · 8.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 8.8; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linuxfoundation	nats-server	cpe:2.3:a:linuxfoundation:nats-server

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linuxfoundation nats-serverbefore 2.11.16
linuxfoundation nats-server2.12.0 and later · before 2.12.7

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

nats-io nats-server
- < 2.11.16, >= 2.12.0-preview.1, < 2.12.6affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	nats-server	from 0	—
Debian:14	nats-server	before 2.14.1-1	2.14.1-1

Same product

linuxfoundation: all records

Other highest-scoring records for the same primary product.

CVE-2020-26892The JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of how expired credentials are handled.
40Plan
CVE-2022-28357NATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended path to a management action from a management accou
39Monitor
CVE-2020-28466Denial of Service (DoS)
31Monitor

Published before and after this one in the same product

← EarlierCVE-2026-58251Jul 8, 2026 · NATS Server: Queue Subscribe Authz Bypass
26Monitor
← EarlierCVE-2026-58252Jul 8, 2026 · NATS Server: Subscribe Authz Bypass via Wildcard-Overlap
26Monitor
Later →CVE-2026-58254Jul 8, 2026 · NATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-Dest permission check
21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
azl3 telegraf 1.31.0-23 on Azure Linux 3.0	1.31.0-24 · CBL-Mariner Releases	Microsoft (MSRC)
debian:nats-server	2.14.1-1 · Debian:14	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-33215106 days apartNATS is vulnerable to MQTT hijacking via Client ID
26Monitor
CVE-2026-33246105 days apartNATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers
21Monitor
CVE-2026-33248105 days apartNATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching
16Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

CVE-2026-582130 days apartNATS Server: MQTT SUBSCRIBE Protocol Injection via Leaf Node/Route Forwarding allows arbitrary NATS command injection
28Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone on the same network segment can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: low · data can be read
Integrity: high · data or configuration can be modified
Availability: low · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector: Adjacent
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Changed
Confidentiality impact: Low
Integrity impact: High
Availability impact: Low

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

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References

github.com/nats-io/nats-server/commit/7b81dd455ea95960090a84858c7662827948d1b6

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records