Vulnerability · Published May 27, 2026 · Assigned by GitHub_M

CVE-2026-44319free5GC: NEF crashes via logger.Fatal on PFD notification delivery failure (attacker-controlled notifyUri)

High 7.5

In plain English

A high-severity improper input validation in free5gc from free5gc. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 65.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF terminates the entire process when a stored PFD-subscription notifyUri cannot be reached. In PfdChangeNotifier.FlushNotifications(), the notifier calls NnefPFDmanagementNotify(...) and on any delivery error invokes logger.PFDManageLog.Fatal(err), which is os.Exit(1)-equivalent in Go. An attacker who can create a PFD subscription with an attacker-chosen notifyUri and then trigger a PFD change can deterministically kill NEF on the asynchronous delivery attempt -- the process exits with status 1, dropping NEF's entire SBI surface until restart. This vulnerability is fixed in 4.2.2.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/free5gc/nef	1.2.3	GHSA-rxrq-fv76-26pr
Go	github.com/free5gc/nef	1.2.3	GO-2026-5647

Affected products (as reported)

Vendor	Product	Versions
free5gc	free5gc	< 4.2.2

Weakness: CWE-20, CWE-617, CWE-755 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/free5gc/free5gc/security/advisories/GHSA-rxrq-fv76-26pr x_refsource_CONFIRM
https://github.com/free5gc/free5gc/issues/924 x_refsource_MISC
https://github.com/free5gc/nef/pull/25 x_refsource_MISC
https://github.com/free5gc/nef/commit/f110517b1189801950b50668a593398687049074 x_refsource_MISC