NVD / CVE Program· CNA GitHub_M

CVE-2026-58210: NATS Server: MQTT partial CONNECT packets can exhaust pre-auth memory

Noroxi assessment

Priority: Monitor (action score 30/100)

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: 0.74% (FIRST EPSS); higher than 54.6% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: nats-server (Debian:14) 2.14.3-1; nats-server2.12 (Red Hat:hummingbird:1) 0:2.12.12-1.hum1; nats-server2.14 (Red Hat:hummingbird:1) 0:2.14.3-1.hum1.

Low priority for now. Upgrade to nats-server (Debian:14) 2.14.3-1; nats-server2.12 (Red Hat:hummingbird:1) 0:2.12.12-1.hum1; nats-server2.14 (Red Hat:hummingbird:1) 0:2.14.3-1.hum1 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 2.14.3 and 2.12.12, an unauthenticated MQTT client could cause the server to retain large incomplete MQTT CONNECT packets before authentication completed, consuming server memory while the parser waited for the advertised MQTT packet length. This issue is fixed in versions 2.14.3 and 2.12.12.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Jul 8, 2026
Updated: Oct 25, 2026
EPSS: 0.7% · 54th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.7%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 7.5; 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 2.12.12
linuxfoundation nats-server2.14.0 and later · before 2.14.3

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
- < 2.12.12, >= 2.14.0-RC.1, < 2.14.3affected

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 2.14.3-1	2.14.3-1
Red Hat:hummingbird:1	nats-server2.12	before 0:2.12.12-1.hum1	0:2.12.12-1.hum1
Red Hat:hummingbird:1	nats-server2.14	before 0:2.14.3-1.hum1	0:2.14.3-1.hum1

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-2026-58253NATS Server: Route API Auth Bypass
35Monitor

Published before and after this one in the same product

← EarlierCVE-2026-33249Mar 25, 2026 · NATS: Message tracing can be redirected to arbitrary subject
17Monitor
← EarlierCVE-2026-58209Jul 8, 2026 · NATS Server: MQTT retained and QoS replay bypass subscribe deny filters
17Monitor
Later →CVE-2026-58213Jul 8, 2026 · NATS Server: MQTT SUBSCRIBE Protocol Injection via Leaf Node/Route Forwarding allows arbitrary NATS command injection
28Monitor

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
debian:nats-server	2.14.3-1 · Debian:14	Package registry (OSV)
red hat:nats-server2.12	0:2.12.12-1.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:nats-server2.14	0:2.14.3-1.hum1 · Red Hat:hummingbird:1	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.

No nightly-computed relations.

Chain candidates

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

—

Bug bounty scope

No known public program.

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

Technical details

Attack conditions

Anyone who can reach it over the internet 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: none
Integrity: none
Availability: high · the service can be disrupted

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

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

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

nvd-secondary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

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

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

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

Endpoint Denial of ServiceT1499

Change log

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/nats-io/nats-server/commit/bce9ef39469e610aeddb819194ceb7f7edfc0861

Show all references (4 more)

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

All records