CVE-2026-44320: Free5gc authentication bypass (CVSS 7.3)

Description

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the nnef-callback route group without inbound OAuth2/bearer-token authorization. A forged or arbitrary bearer token (e.g. Authorization: Bearer not-a-real-token) is enough to reach the SMF-callback handler -- the callback body is parsed and dispatched into NEF business logic instead of being rejected at the auth boundary. Same root cause as the other NEF SBI findings: the route group is mounted without any inbound auth middleware. NEF does not authenticate the producer NF identity before processing callback content; if an attacker can guess or obtain a valid NotifId, this missing auth boundary lets forged callbacks act on real subscription state. The route group is also reachable even when the runtime ServiceList does not declare it (it lists only nnef-pfdmanagement and nnef-oam). This vulnerability is fixed in 4.2.2.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityLow

IntegrityLow

AvailabilityLow

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

Affected products

Free5gc< 4.2.2

Remediation

Fixed in

Free5gc≥ 4.2.2

Patch & vendor advisories

References

https://github.com/free5gc/free5gc/issues/860ExploitIssue Tracking
https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mfExploitVendor Advisory
https://github.com/free5gc/nef/pull/24Issue TrackingPatch

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-44320 being actively exploited?

CVE-2026-44320 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.38%.

How severe is CVE-2026-44320?

CVE-2026-44320 has a CVSS 3.1 base score of 7.3, rated high. EPSS estimates a 0.38% probability of exploitation.

Which products are affected by CVE-2026-44320?

Affected products include Free5gc.

How do I fix CVE-2026-44320?

Upgrade affected software to a fixed version, for example Free5gc 4.2.2 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-44320 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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