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NVD / CVE Program· CNA GitHub_M

CVE-2026-58250: NATS Server: Pre-auth server crash via double INFO in leafnode handshake

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 55% 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: 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 2.12.8 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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Jul 8, 2026
Updated
Oct 25, 2026
EPSS
0.7% · 55th percentile

Report tools

JSON

Action score

30

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

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

VendorProduct
linuxfoundationnats-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 2.11.17
  • linuxfoundation nats-server2.12.0 and later · before 2.12.8

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

    • < 2.11.17, >= 2.12.0-preview.1, < 2.12.8affected

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12nats-serverfrom 0—
Debian:14nats-serverbefore 2.14.1-12.14.1-1

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…
    39Monitor
  • CVE-2026-58253NATS Server: Route API Auth Bypass
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-58213Jul 8, 2026 · NATS Server: MQTT SUBSCRIBE Protocol Injection via Leaf Node/Route Forwarding allows arbitrary NATS command injection
    28Monitor
  • ← EarlierCVE-2026-58214Jul 8, 2026 · NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for CVE-2026-33217)
    17Monitor
  • Later →CVE-2026-58251Jul 8, 2026 · NATS Server: Queue Subscribe Authz Bypass
    26Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
azl3 telegraf 1.31.0-23 on Azure Linux 3.01.31.0-24 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:nats-server2.14.1-1 · Debian:14Package 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.

No history yet (it accumulates with the daily EPSS job).

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-2026-29785105 days apartNATS Server panic via malicious compression on leafnode port
    30Monitor

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-476 · NULL Pointer Dereference

CVSS vector

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

nvd-secondary

Attack context

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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

References

Show all references (4 more)

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

All records