CVE-2026-44320
free5GC: NEF nnef-callback route group is unauthenticated; forged callback requests are accepted into the processing path
No known exploitation. EPSS puts it in the 29th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.4% chance of exploitation activity in the next 30 days, which ranks it in the 29th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
5 events over 1 day, from the signal feeds we watch.
- Patch availablerecord updated
- Publishedweakness classified, att&ck mapped
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Scored 7.3 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality LowSome restricted information is disclosed, but limited in scope
- Integrity LowData modification is possible but limited in scope or consequence
- Availability LowReduced performance or intermittent disruption of service
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
Watch the software you run.
My Stack ranks new CVEs for your products by real-world exploitation, so the next serious one reaches you without reading every advisory.
We'll flag the next CVE, public exploit or patch for Free5gc, not every advisory.
A free account adds
- The full version matrix and every affected product
- Exploit links, proofs of concept and Metasploit modules
- Email alerts for the products you watch
- The same data over REST API, MCP and CLI