Unauthenticated subscriber disclosure via missing PCF middleware
Published May 27, 2026 · Updated May 27, 2026
Missing authorization in free5GC before 4.2.2 allows remote attackers to access PCF SM policy handlers and disclose subscriber SUPIs. In NewServer(), smPolicyGroup registers Npcf_SMPolicyControl routes without RouterAuthorizationCheck, so unauthenticated requests reach business logic. Network access to the PCF SBI interface is required; subscriber disclosure further requires existing UE, session, and policy context, while the exposed handlers also permit unauthenticated policy operations.
Summary
What happened
Missing authorization in free5GC before 4.2.2 allows remote attackers to access PCF SM policy handlers and disclose subscriber SUPIs. In NewServer(), smPolicyGroup registers Npcf_SMPolicyControl routes without RouterAuthorizationCheck, so unauthenticated requests reach business logic. Network access to the PCF SBI interface is required; subscriber disclosure further requires existing UE, session, and policy context, while the exposed handlers also permit unauthenticated policy operations.
The record
- CVE
- CVE-2026-42083
- Published
- May 27, 2026
- Updated
- May 27, 2026
- Vendor
- free5GC
- Product
- free5GC
- Classifications
- CWE-862
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 27, 2026CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.2.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- free5GC issue 844 no-auth PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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