free5GC: PCF npcf-smpolicycontrol POST /sm-policies panics on downstream UDR/OpenAPI 404 via nil pointer dereference

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free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's PCF POST /npcf-smpolicycontrol/v1/sm-policies handler (HandleCreateSmPolicyRequest) panics with a nil-pointer dereference when a downstream OpenAPI consumer call (UDR lookup) returns 404 Not Found and the consumer wrapper returns err != nil together with a nil response struct. The handler logs the OpenAPI error and continues executing instead of returning, then dereferences the nil response struct on a subsequent line and panics. Gin recovery converts the panic into HTTP 500, so a single attacker-shaped POST returns 500 instead of a clean 4xx whenever the downstream lookup fails. The PCF process keeps running. The trigger is a single POST containing input that causes the downstream UDR lookup to fail (e.g. an unknown DNN). In 4.2.1 this endpoint is also reachable WITHOUT an Authorization header because the PCF Npcf_SMPolicyControl route group is mounted without inbound auth middleware. This vulnerability is fixed in 4.2.2.

Source published

27 May 2026 15:52:07 UTC

Source modified

27 May 2026 17:54:45 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's PCF POST /npcf-smpolicycontrol/v1/sm-policies handler (HandleCreateSmPolicyRequest) panics with a nil-pointer dereference when a downstream OpenAPI consumer call (UDR lookup) returns 404 Not Found and the consumer wrapper returns err != nil together with a nil response struct. The handler logs the OpenAPI error and continues executing instead of returning, then dereferences the nil response struct on a subsequent line and panics. Gin recovery converts the panic into HTTP 500, so a single attacker-shaped POST returns 500 instead of a clean 4xx whenever the downstream lookup fails. The PCF process keeps running. The trigger is a single POST containing input that causes the downstream UDR lookup to fail (e.g. an unknown DNN). In 4.2.1 this endpoint is also reachable WITHOUT an Authorization header because the PCF Npcf_SMPolicyControl route group is mounted without inbound auth middleware. This vulnerability is fixed in 4.2.2.

Source published

May 27, 2026, 3:52:07 PM (timezone not stated)

Source modified

May 27, 2026, 5:54:45 PM (timezone not stated)

Observed here

9 Nov 2026 11:03:37 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's PCF POST /npcf-smpolicycontrol/v1/sm-policies handler (HandleCreateSmPolicyRequest) panics with a nil-pointer dereference when a downstream OpenAPI consumer call (UDR lookup) returns 404 Not Found and the consumer wrapper returns err != nil together with a nil response struct. The handler logs the OpenAPI error and continues executing instead of returning, then dereferences the nil response struct on a subsequent line and panics. Gin recovery converts the panic into HTTP 500, so a single attacker-shaped POST returns 500 instead of a clean 4xx whenever the downstream lookup fails. The PCF process keeps running. The trigger is a single POST containing input that causes the downstream UDR lookup to fail (e.g. an unknown DNN). In 4.2.1 this endpoint is also reachable WITHOUT an Authorization header because the PCF Npcf_SMPolicyControl route group is mounted without inbound auth middleware. This vulnerability is fixed in 4.2.2.

Source published

27 May 2026 17:16:36 UTC

Source modified

14 Oct 2026 20:10:00 UTC

Observed here

25 Oct 2026 10:17:21 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

### Summary free5GC's PCF `POST /npcf-smpolicycontrol/v1/sm-policies` handler (`HandleCreateSmPolicyRequest`) panics with a nil-pointer dereference when a downstream OpenAPI consumer call (UDR lookup) returns `404 Not Found` and the consumer wrapper returns `err != nil` together with a nil response struct. The handler logs the OpenAPI error and continues executing instead of returning, then dereferences the nil response struct on a subsequent line and panics. Gin recovery converts the panic into `HTTP 500`, so a single attacker-shaped POST returns 500 instead of a clean 4xx whenever the downstream lookup fails. The PCF process keeps running. The trigger is a single POST containing input that causes the downstream UDR lookup to fail (e.g. an unknown DNN). In v4.2.1 this endpoint is also reachable WITHOUT an `Authorization` header because the PCF `Npcf_SMPolicyControl` route group is mounted without inbound auth middleware (see free5gc/free5gc#844). So in the validation lab the trigger is fully unauthenticated. ### Details Validated against the PCF container in the official Docker compose lab. - free5GC version: `v4.1.0` (originally reported on v4.1.0; same defect present in v4.2.1) - PCF endpoint: `http://10.100.200.9:8000` Vulnerable handler path (paraphrased from the captured stack trace): ``` [INFO][PCF][SMpolicy] Handle CreateSmPolicy [ERRO][PCF][Consumer] openapi error: 404, Not Found [ERRO][PCF][GIN] panic: runtime error: invalid memory address or nil pointer dereference github.com/free5gc/pcf/internal/sbi/processor.(*Processor).HandleCreateSmPolicyRequest /go/src/free5gc/NFs/pcf/internal/sbi/processor/smpolicy.go:82 +0x562 github.com/free5gc/pcf/internal/sbi.(*Server).HTTPCreateSMPolicy /go/src/free5gc/NFs/pcf/internal/sbi/api_smpolicy.go:86 +0x405 ``` The handler's UDR-failure branch logs the OpenAPI error but does not return; the next line dereferences the nil response struct. Code evidence (paths in `free5gc/pcf`): - Panic site: - `NFs/pcf/internal/sbi/processor/smpolicy.go:82` - Route dispatch: - `NFs/pcf/internal/sbi/api_smpolicy.go:86` ### PoC Reproduced end-to-end against the running PCF at `http://10.100.200.9:8000`. Send a single POST whose `dnn` is unknown to UDR -- this drives the downstream OpenAPI call to return `404 Not Found`, which then triggers the nil-deref panic: ``` curl -sS -X POST 'http://10.100.200.9:8000/npcf-smpolicycontrol/v1/sm-policies' \ -H 'Content-Type: application/json' \ -d '{ "supi":"imsi-208930000000003", "pduSessionId":1, "dnn":"internet-bad", "sliceInfo":{"sst":1,"sd":"010203"}, "servingNetwork":{"mcc":"208","mnc":"93"}, "accessType":"3GPP_ACCESS", "notificationUri":"http://smf.free5gc.org:8000/npcf-smpolicycontrol/v1/notify" }' ``` Observed response: `HTTP 500 Internal Server Error` with empty body. PCF container logs show: ``` [INFO][PCF][SMpolicy] Handle CreateSmPolicy [ERRO][PCF][Consumer] openapi error: 404, Not Found [ERRO][PCF][GIN] panic: runtime error: invalid memory address or nil pointer dereference ...HandleCreateSmPolicyRequest at smpolicy.go:82... ``` The Gin recovery middleware catches the panic (the captured stack trace runs inside `ginRecover.func2.1`), so the PCF process keeps serving other requests; the realized impact is per-request `HTTP 500` on this endpoint whenever the downstream lookup fails. ### Impact NULL pointer dereference (CWE-476) caused by improper handling of an exceptional branch (CWE-754): the UDR-failure branch logs the OpenAPI error but does not return, then dereferences the nil response struct. The intended behavior is to return a controlled `4xx`/`5xx` `ProblemDetails` and stop processing. Gin recovery catches the panic, so the PCF process is NOT killed and other endpoints continue serving. The realized impact is per-request: any unauthenticated POST that drives the downstream UDR lookup to a `404` returns `HTTP 500` (with empty body and a stack trace in PCF logs) instead of a controlled error response. No Confidentiality impact (the response is `500` with empty body). No persistent Integrity impact (the panic happens before any state mutation). Availability impact is limited to per-request degradation. The endpoint remains reachable to unauthenticated attackers via the route-group auth gap separately tracked in free5gc/free5gc#844. Affected: free5gc v4.2.1 (originally reported against v4.1.0; same defect present). Upstream issue: https://github.com/free5gc/free5gc/issues/803 Upstream fix: https://github.com/free5gc/pcf/pull/62

Source published

8 May 2026 22:39:43 UTC

Source modified

25 Jun 2026 23:11:02 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH

free5GC's PCF npcf-smpolicycontrol POST /sm-policies panics on downstream UDR/OpenAPI 404 via nil pointer dereference in github.com/free5gc/pcf

Source published

25 Jun 2026 22:34:38 UTC

Source modified

25 Jun 2026 23:01:29 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.