Executive brief
free5gc is an open-source implementation of a 5G telecommunications core network. The Charging Function (CHF) component contains a bug in the RechargePut endpoint that crashes the service when it receives malformed recharging requests missing the required underscore delimiter. An attacker can trigger this crash repeatedly to cause a denial of service, making the charging system unavailable.
Technical details
The vulnerability is an improper input validation flaw (CWE-129: improper validation of array index) in the RechargePut function within the Converged Charging Handler (CHF) service. The function splits the rechargingInfo path parameter by underscore and immediately accesses the second element without checking the resulting slice length. A crafted PUT request to the /nchf-convergedcharging/v3/recharging/ endpoint with a parameter lacking an underscore triggers a runtime panic (index out of range), crashing the goroutine and causing the server to return HTTP 500. The attack requires only network access to the CHF endpoint and no authentication. A fix involves validating the slice length before array access.
Affected products
- free5gc free5gc v4.0.1
Timeline
- 2026-01-01: disclosed: Issue #760 opened on GitHub
- 2026-08-27: advisory: CVE-2026-30071 published