free5GC is an open-source implementation of the 5G core network
Why It Matters
Analysis dossierWhy It Matters
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.
High
Unknown
Unknown
Risk basis: SOC ecosystem technology relevance; HIGH severity; No confirmed exploitation signal in current enrichment
Affected Products & Remediation
1 source-backed product- free5gc free5gc · < 4.2.2 · NVD CPE · Source
Vendor or catalog guidance (source)
Not provided by source
Known exploitation (source facts)
Only what a source states. Unknown means no source has said either way; it is not "not exploited".
- CISA KEV
- Unknown
- Exploited (source statement)
- Unknown
- Publicly disclosed (source)
- Unknown
Suggested hunting (rule-based inference)
SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.
Matched authentication-weakness (CWE-306); authorization-bypass (CWE-862)
Exposure
- Identify affected authentication surfaces and compare versions with the advisory.Telemetry: Application inventory · A CWE match is not proof of local exposure. · Rule authentication-weakness
- Locate affected authorization controls and verify deployed versions.Telemetry: Application inventory · The source must identify the affected control. · Rule authorization-bypass
Exploitation evidence
- Review unexpected successful sign-ins and changes to privileged accounts on affected systems.Telemetry: SigninLogs · Access anomalies are relevant to authentication weaknesses. · Rule authentication-weakness
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Exploitation evidence
- Review privileged operations performed by unexpected users on affected deployments.Telemetry: Application audit logs · Authorization anomalies can support a targeted hunt. · Rule authorization-bypass
Response
- Verify the vendor fix and review privileged access after remediation.Telemetry: Identity audit logs · Post-change review checks the response. · Rule authentication-weakness
CISA KEV Record
CISA KEV status was not determined for this record.
Change History & Source Data
— No recorded material change
- CNA / source
- security-advisories@github.com
- Record status · verification
- UPDATED · NVD API
- CPE
- cpe:2.3:a:free5gc:free5gc:*:*:*:*:*:*:*:*
Evidence & Provenance
Linked by the query's stored exact CVE association. Review required tables and validation status before use.
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-44320"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel descCorrelated briefings
— No published briefing references this CVE