CVE-2026-33062
Published: 20 March 2026
Summary
CVE-2026-33062 is a high-severity Improper Access Control (CWE-284) vulnerability in Free5Gc Free5Gc. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 47.4th 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 are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2026-33062 is an Improper Input Validation vulnerability in the Network Repository Function (NRF) component of free5GC, an open-source 5G core network implementation. Versions of free5GC NRF prior to 1.4.2 are affected, with all deployments utilizing the NRF discovery service vulnerable. The issue stems from the `EncodeGroupId` function, which accesses array indices [0], [1], and [2] on split data without first validating the input length. Insufficient separator characters in the input trigger a "index out of range" panic. The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and is associated with CWE-284.
A remote, unauthenticated attacker can exploit this vulnerability by sending a crafted HTTP GET request to the NRF service with a malformed `group-id-list` parameter. This causes the service to panic and crash, resulting in a complete denial of service for the NRF discovery service until it is restarted.
Advisories and patch notes recommend upgrading to free5GC NRF version 1.4.2, which resolves the issue via a specific commit. No application-level workaround exists, though restricting access to the NRF API to trusted sources only is advised as a mitigation. Relevant resources include the GitHub issue tracker, security advisory, fixing commit, and pull request.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-13511
Vulnerability details
free5GC is an open source 5G core network. free5GC NRF prior to version 1.4.2 has an Improper Input Validation vulnerability leading to Denial of Service. All deployments of free5GC using the NRF discovery service are affected. The `EncodeGroupId` function attempts…
more
to access array indices [0], [1], [2] without validating the length of the split data. When the parameter contains insufficient separator characters, the code panics with "index out of range". A remote attacker can cause the NRF service to panic and crash by sending a crafted HTTP GET request with a malformed `group-id-list` parameter. This results in complete denial of service for the NRF discovery service. free5GC NRF version 1.4.2 fixes the issue. There is no direct workaround at the application level. The recommendation is to apply the provided patch or restrict access to the NRF API to trusted sources only.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct match to application/system exploitation causing crash/DoS via crafted input to NRF service (T1499.004).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-10 directly mandates validation of the malformed group-id-list parameter prior to processing, preventing the index out of range panic in the EncodeGroupId function.
SI-2 requires timely remediation of the specific flaw via patching to free5GC NRF version 1.4.2, eliminating the improper input validation vulnerability.
SC-5 protects the NRF service against denial-of-service crashes triggered by remote attackers sending crafted HTTP GET requests with insufficient separator characters.