CVE-2026-33062: free5GC NRF Discovery EncodeGroupId Function Panics on Malformed group-id-list Parameter

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-20 · updated 2026-06-17
Weakness: CWE-284

Description

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 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.

Affected products

free5gc: before 1.4.2 — fixed in 1.4.2

How to fix

Upgrade to a fixed version: free5gc 1.4.2. Check the vendor advisory for mitigations.

References

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