CVE-2026-53551
MediumCVSS 6.9Exploitation Probability (EPSS)
Low risk44th percentile - higher than 44% of all known CVEs
Summary
In free5GC prior to version 1.4.5, the AUSF does not validate the supiOrSuci field in UE authentication requests. Null bytes and other control characters pass through JSON parsing and are forwarded to the UDM in an unescaped URL path, causing Go's net/url.Parse() to fail and return HTTP 500 with stack trace leakage. An unauthenticated attacker can cause denial of service for all subscribers attempting authentication through the affected AUSF.
Risk Assessment
An attacker can cause a complete denial of authentication service for all 5G network subscribers, preventing them from accessing the network.
Recommendation
Update free5GC to version 1.4.5 or later.
Other vulnerabilities in free5GC
See all- CVE-2026-106805Unknown
A resource exhaustion issue exists in Free5GC v4.2.3 during PFCP Session Establishment failure handling. When the SMF does not receive a PFCP Session Establishment Response from the UPF, allocated UE IP address resources are not properly released, and repeated failures can exhaust the UE IP address pool.
- CVE-2026-55068Critical
free5GC in version 4.2.2 and earlier has a vulnerability in the NRF RegisterNFInstance handler that accepts NF Profiles without enforcing UUID format, nfStatus enum values, heartBeatTimer ranges, mandatory profile fields, or nfServices.ipEndPoints address constraints. Invalid profiles are persisted in MongoDB and returned by NFDiscover, allowing an attacker with SBI access to advertise attacker-controlled endpoints and redirect control-plane signaling. This issue is fixed in version 4.2.3.
- CVE-2026-94043Medium
A vulnerability was determined in Free5GC up to 4.2.3 affecting unknown code of file /corefuzzer_deps/free5gc/NFs/amf/internal/gmm/handler.go (Gmm Handler component). Manipulation causes a race condition. The attack can be initiated remotely and the patch is identified as e323b01464355781b8b8d5dd695e05cbc00a62f2.
- CVE-2026-47780Medium
In free5GC 4.2.3 and earlier, HandleCreateEeSubscriptions and HandleQueryeesubscriptions in internal/sbi/api_datarepository.go validate the ueId path value with a regular expression whose final .+ alternative accepts any non-empty string instead of restricting identifiers to supported SUPI and GPSI formats. An actor with network reachability to the UDR SBI can submit a non-3GPP identifier to /nudr-dr/v2/subscription-data/{ueId}/context-data/ee-subscriptions, causing it to pass validation and enter the normal create or query flow. Invalid identifiers can be persisted and retrieved as subscription records.
- CVE-2026-75439High
An issue in Free5GC v.4.2.2 allows a remote attacker to cause a denial of service via the UPF component.
- CVE-2026-55785Low
free5GC before version 1.4.5 has a vulnerability in the AUSF component where cryptographic comparisons (RES* and XRES*, AT_MAC and XMAC) are performed using ordinary equality helpers, and the expected XRES* value is logged at INFO level. This can expose authentication material to parties with access to AUSF logs.
- CVE-2026-55784High
Vulnerability in free5GC (5G core network implementation) version 1.4.4 and earlier. The AUSF component stores authentication state in a global map, allowing an attacker with access to the SBI/N12 interface to send concurrent authentication requests for the same SUPI, overwriting the context and denying authentication to the selected subscriber. No fix available.
- CVE-2026-30073High
A vulnerability in the NssaiAvailabilitySubscriptionCreate component of free5gc v4.0.1 allows an attacker to cause a Denial of Service (DoS) via a crafted POST request.
- CVE-2026-30072High
A NULL pointer dereference in the CDR processing path of free5gc v4.0.1 allows attackers to cause a Denial of Service (DoS) by supplying a crafted payload.
- CVE-2026-30071High
An issue in the RechargePut function of free5gc v4.0.1 allows attackers to cause a Denial of Service (DoS) via crafted input.
Original NVD description (English source)
free5GC is an open-source implementation of the 5G core network. Prior to 1.4.5, the free5GC AUSF (Authentication Server Function) does not validate the supiOrSuci field in UE authentication requests. Null bytes (\x00) and other control characters pass through JSON parsing unchanged and are forwarded to the UDM in an unescaped URL path. This causes Go's net/url.Parse() to fail, returning HTTP 500 "System failure" and leaking internal stack traces. An unauthenticated attacker can trigger this at scale causing denial of service for all subscribers attempting authentication through the affected AUSF. This vulnerability is fixed in 1.4.5.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS