CVE-2026-40245
Info Disclosure in Free5Gc ≤ 4.2.1
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NSummary
CVE-2026-40245 is a high-severity Exposure of Sensitive Information to an Unauthorized Actor (CWE-200) vulnerability in Free5Gc Free5Gc. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Token Impersonation/Theft (T1134.001); ranked at the 41th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-23 (Data Mining Protection) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-40245 is an information disclosure vulnerability affecting Free5GC, an open-source Linux Foundation project for 5G mobile core networks, in versions 4.2.1 and below. The issue resides in the Unified Data Repository (UDR) service, where the handler for the GET /nudr-dr/v2/application-data/influenceData/subs-to-notify endpoint responds with an HTTP 400 error for missing required query parameters but fails to return, allowing execution to continue into the processor function. This appends the full list of Traffic Influence Subscriptions, including sensitive SUPI/IMSI subscriber identifiers, to the response body. A similar bypass occurs with a malformed snssai parameter due to the same missing return pattern. The vulnerability is rated 7.5 on the CVSS 3.1 scale (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) and maps to CWEs 200, 202, and 209.
An unauthenticated attacker with network access to the 5G Service Based Interface (SBI) can exploit this by sending a single parameterless HTTP GET request to the vulnerable endpoint, retrieving the complete list of stored subscriber identifiers. The exposure of SUPI, the most sensitive subscriber identifier in 5G networks, undermines the privacy protections of the 3GPP SUCI concealment mechanism at the core network level, potentially enabling tracking, impersonation, or further attacks on subscribers.
For mitigation details, refer to the official GitHub security advisory at https://github.com/free5gc/free5gc/security/advisories/GHSA-wrwh-rpq4-87hf.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23133
Vulnerability Data
Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions 4.2.1 and below contain an information disclosure vulnerability in the UDR (Unified Data Repository) service. The handler for GET /nudr-dr/v2/application-data/influenceData/subs-to-notify sends an HTTP 400 error…
more
response when required query parameters are missing but does not return afterward. Execution continues into the processor function, which queries the data repository and appends the full list of Traffic Influence Subscriptions, including SUPI/IMSI values, to the response body. An unauthenticated attacker with network access to the 5G Service Based Interface can retrieve stored subscriber identifiers with a single parameterless HTTP GET request. The SUPI is the most sensitive subscriber identifier in 5G networks, and its exposure undermines the privacy guarantees of the 3GPP SUCI concealment mechanism at the core network level. A similar bypass exists when sending a malformed snssai parameter due to the same missing return pattern.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 7 hardening rules · 6 OS baselines
V10.4.9V11.7.1V14.1.2V14.2.4
Mitigating Controls (NIST 800-53 r5) AI
Access enforcement directly stops unauthorized actors from obtaining sensitive information.
Information flow enforcement structurally prevents sensitive data from reaching unauthorized recipients.
Protection of information at rest prevents unauthorized exposure of stored sensitive data.
Transmission confidentiality mechanisms stop exposure of sensitive data on the wire.
si-11 directly requires error messages to avoid revealing exploitable information about the system or its data.
AC-23 directly requires mechanisms to protect against unauthorized data mining and inference from statistical queries that would expose sensitive information.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
PR.AA-05 directly enforces least-privilege authorization that blocks most unauthorized disclosures, yet CWE-200 also arises from logging, error messages, and side-channel paths that access controls alone do not address.
PR.DS-10 mostly prevents CWE-200 by directly eliminating unauthorized access to sensitive data-in-use, yet only partially addresses the weakness because CWE-200 spans many other exposure vectors outside runtime protection.
PR.IR-01's segmentation/zero-trust controls largely eliminate network-level unauthorized access paths that enable exposure, yet CWE-200 spans many additional vectors (API responses, logs, app logic) that network controls alone cannot close.
Secure SDLC practices catch most exposure flaws via design, testing and release controls, yet CWE-200 spans runtime/config issues a single development outcome cannot fully close.
Behavior analytics on query activity can detect inference attempts but does not prevent exposure at query time.
PR.AA-01 supplies proper credential lifecycle controls that reduce unauthorized access paths, yet leaves many other exposure vectors (error messages, logging, side channels, etc.) unaddressed.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Restricting anonymous or unknown access and encrypting high-value information limits the exposure of sensitive data that would otherwise be obtainable by unauthorized actors.
Suppressing system details, error specifics, and previous log-on information until successful authentication reduces the information an unauthenticated attacker can gather.
By requiring owners to assign sensitivity labels and corresponding handling rules, the control ensures that information is not left unmarked and therefore reduces the chance that sensitive data will be exposed to unauthorized actors.
Requiring encryption, access controls, and recipient authentication for transfers directly reduces the chance that sensitive data reaches an unauthorized observer.
Access control limits who can run queries that could expose sensitive information via inference.
Secure delivery, protected storage, and confidentiality of allocation records limit exposure of authentication material to unauthorized observers.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Ubuntu 22.04 (1 rule)
- V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-200
Ubuntu 24.04 (2 rules)
- V-270647 Ubuntu 24.04 LTS must not have the telnet package installed. prevents CWE-200
- V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-200
Windows 10 (1 rule)
- V-220737 Administrative accounts must not be used with applications that access the Internet, such as web browsers, or with potential Internet sources, such as email. prevents CWE-200
Windows Server 2016 (1 rule)
- V-224974 Domain-created Active Directory Organizational Unit (OU) objects must have proper access control permissions. prevents CWE-200
Windows Server 2019 (1 rule)
- V-205743 Windows Server 2019 organization created Active Directory Organizational Unit (OU) objects must have proper access control permissions. prevents CWE-200
Windows Server 2022 (1 rule)
- V-254395 Windows Server 2022 organization created Active Directory Organizational Unit (OU) objects must have proper access control permissions. prevents CWE-200