CVE-2026-44321 | free5GC: SMF UPI POST /upi/v1/upNodesLinks exits the SMF process on overlapping UE pools (unauthenticated, reachable Fatalf)

Exp

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. The POST /upi/v1/upNodesLinks create-or-update handler accepts attacker-controlled JSON and passes it directly into UpNodesFromConfiguration(), which calls logger.InitLog.Fatalf(...) on several validation failures. One confirmed path is the UE-IP-pool overlap check: a single unauthenticated POST that adds a new UPF whose pool overlaps an existing UPF terminates the entire SMF process (docker ps shows Exited (1)), not just the goroutine. This vulnerability is fixed in 4.2.2.

Published: 2026-05-27 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-44321 is rated Exploit Available (54.9/100): CVSS High severity, with low exploitation likelihood (EPSS 0.36%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-44321

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-44321

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-23 0.34% 0.36% +0.03%
2 2026-06-15 0.05% 0.34% +0.29%
3 2026-06-02 — 0.05% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-44321

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-44321

GitHub Security Advisory for CVE-2026-44321

GHSA-44qj-cghf-9p97 · Severity: high · Ecosystem: go — free5GC's SMF UPI POST /upi/v1/upNodesLinks exits the SMF process on overlapping UE pools (unauthenticated, reachable Fatalf)

Affected software / configurations for CVE-2026-44321

Vendor Product Version Raw CPE
free5gc free5gc < 4.2.2 cpe:2.3:a:free5gc:free5gc:*:*:*:*:*:*:*:*

References for CVE-2026-44321

cvelogic Threat Intelligence