CVE-2026-44321Public exploitNetwork attack vector

Unauthenticated SMF crash via fatal pool validation

Published May 27, 2026 · Updated May 27, 2026

Denial of service in free5GC before 4.2.2 allows remote attackers to crash the SMF via an unauthenticated UPI topology update. The POST /upi/v1/upNodesLinks handler passes attacker-controlled pool data into UpNodesFromConfiguration(), where overlap validation calls logger.InitLog.Fatalf and exits the process. Network access to the SMF SBI is sufficient; one overlapping UE pool request drops all SMF SBI services until restart.

CVSS severity7.5
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in free5GC before 4.2.2 allows remote attackers to crash the SMF via an unauthenticated UPI topology update. The POST /upi/v1/upNodesLinks handler passes attacker-controlled pool data into UpNodesFromConfiguration(), where overlap validation calls logger.InitLog.Fatalf and exits the process. Network access to the SMF SBI is sufficient; one overlapping UE pool request drops all SMF SBI services until restart.

The record

CVE
CVE-2026-44321
Published
May 27, 2026
Updated
May 27, 2026
Vendor
free5GC
Product
free5GC
Classifications
CWE-862, CWE-306, CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

free5GC · free5GCversion=< 4.2.2

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
CWE-306Missing Authentication for Critical Function
CWE-617Reachable Assertion
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo