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CVE-2026-44328

free5GC: SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating

8.2 HighFix available

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry. This vulnerability is fixed in 4.2.2.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
High

Exploit likelihood

0.32%Up 0.3 points since May 28, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.2

free5GC: SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry. This vulnerability is fixed in 4.2.2.

Record
CVE-2026-44328
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-306, CWE-476, CWE-862
Updated
2026-11-02
EUVDEUVD-2026-32570 8.2

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry. This vulnerability is fixed in 4.2.2.

Record
EUVD-2026-32570
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-p9mg-74mg-cwwr 8.2

free5GC's SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating

Summary

free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware (same root cause as the broader UPI auth gap reported in free5gc/free5gc#887). On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry.

Details

Validated against the SMF container in the official Docker compose lab.

  • Source repo tag: v4.2.1
  • Running Docker image: free5gc/smf:v4.2.1
  • Runtime SMF commit: 8385c00a
  • Docker validation date: 2026-03-22 local (container log timestamp 2026-03-21T23:43:17Z)
  • SMF endpoint: http://10.100.200.6:8000

Control comparison on the same SMF instance:

  • GET /nsmf-oam/v1/ (no token) -> 401 Unauthorized
  • DELETE /upi/v1/upNodesLinks/gNB1 (no token) -> 500 Internal Server Error (panic)

The sibling nsmf-oam returning 401 proves OAuth middleware IS wired in for other SMF route groups; the UPI group specifically is mounted without it.

Vulnerable handler logic (paths in free5gc/smf):

// NFs/smf/internal/sbi/api_upi.go:94..99
if upNode.Type == smf_context.UPNODE_UPF {
    go s.Processor().ReleaseAllResourcesOfUPF(upNode.UPF)
}
upi.UpNodeDelete(upNodeRef)
upNode.UPF.CancelAssociation()   // <-- panics for AN-typed nodes; nil UPF

The Type == UPNODE_UPF guard only protects the asynchronous ReleaseAllResourcesOfUPF call. After that, UpNodeDelete(upNodeRef) runs unconditionally (so the topology mutation lands first), and then upNode.UPF.CancelAssociation() is called unconditionally on a *UPF that is nil for AN nodes by construction.

Code evidence:

  • UPI group mounted WITHOUT auth middleware:
    • NFs/smf/internal/sbi/server.go:76
    • NFs/smf/internal/sbi/server.go:78
  • Protected control comparison (other SMF groups DO use auth):
    • NFs/smf/internal/sbi/server.go:99
    • NFs/smf/internal/sbi/server.go:105
  • Delete handler (panic site):
    • NFs/smf/internal/sbi/api_upi.go:94
    • NFs/smf/internal/sbi/api_upi.go:99
  • AN nodes are constructed without a UPF object (root cause of the nil deref):
    • NFs/smf/internal/context/user_plane_information.go:95
    • NFs/smf/internal/context/user_plane_information.go:97

PoC

Reproduced end-to-end against the running SMF at http://10.100.200.6:8000.

  1. Control: protected sibling OAM route returns 401:
curl -i http://10.100.200.6:8000/nsmf-oam/v1/

HTTP/1.1 401 Unauthorized
  1. Trigger: unauthenticated DELETE on the default AN node gNB1:
curl -i -X DELETE http://10.100.200.6:8000/upi/v1/upNodesLinks/gNB1

HTTP/1.1 500 Internal Server Error
  1. SMF container logs (docker logs --tail 120 smf) show topology mutation landing BEFORE the panic, and the panic stack pointing at api_upi.go:99:
[INFO][SMF][Init] UPNode [gNB1] found. Deleting it.
[INFO][SMF][Init] Delete UPLink [UPF] <=> [gNB1].
[ERRO][SMF][GIN] panic: runtime error: invalid memory address or nil pointer dereference
github.com/free5gc/smf/internal/sbi.(*Server).DeleteUpNodeLink
    /go/src/free5gc/NFs/smf/internal/sbi/api_upi.go:99 +0x298
[INFO][SMF][GIN] | 500 | DELETE | /upi/v1/upNodesLinks/gNB1

The lab state was manually restored after validation by re-creating the AN entry; that POST is restoration-only and is NOT a mitigation.

Impact

Three compounding defects on the same SMF SBI surface:

  1. Missing inbound authentication (CWE-306) and authorization (CWE-862) on the UPI route group, so the trigger is reachable to any off-path network attacker who can reach SMF…
Record
GHSA-p9mg-74mg-cwwr
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-306, CWE-476, CWE-862
Updated
2026-11-02
NVD 8.2

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry. This vulnerability is fixed in 4.2.2.

Record
CVE-2026-44328
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-306, CWE-476, CWE-862
Updated
2026-11-02
OSV 8.2

free5GC: SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry. This vulnerability is fixed in 4.2.2.

Record
CVE-2026-44328
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-306, CWE-476, CWE-862
Updated
2026-11-02
OSVGHSA-p9mg-74mg-cwwr 8.2

free5GC's SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating

Summary

free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware (same root cause as the broader UPI auth gap reported in free5gc/free5gc#887). On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry.

Details

Validated against the SMF container in the official Docker compose lab.

  • Source repo tag: v4.2.1
  • Running Docker image: free5gc/smf:v4.2.1
  • Runtime SMF commit: 8385c00a
  • Docker validation date: 2026-03-22 local (container log timestamp 2026-03-21T23:43:17Z)
  • SMF endpoint: http://10.100.200.6:8000

Control comparison on the same SMF instance:

  • GET /nsmf-oam/v1/ (no token) -> 401 Unauthorized
  • DELETE /upi/v1/upNodesLinks/gNB1 (no token) -> 500 Internal Server Error (panic)

The sibling nsmf-oam returning 401 proves OAuth middleware IS wired in for other SMF route groups; the UPI group specifically is mounted without it.

Vulnerable handler logic (paths in free5gc/smf):

// NFs/smf/internal/sbi/api_upi.go:94..99
if upNode.Type == smf_context.UPNODE_UPF {
    go s.Processor().ReleaseAllResourcesOfUPF(upNode.UPF)
}
upi.UpNodeDelete(upNodeRef)
upNode.UPF.CancelAssociation()   // <-- panics for AN-typed nodes; nil UPF

The Type == UPNODE_UPF guard only protects the asynchronous ReleaseAllResourcesOfUPF call. After that, UpNodeDelete(upNodeRef) runs unconditionally (so the topology mutation lands first), and then upNode.UPF.CancelAssociation() is called unconditionally on a *UPF that is nil for AN nodes by construction.

Code evidence:

  • UPI group mounted WITHOUT auth middleware:
    • NFs/smf/internal/sbi/server.go:76
    • NFs/smf/internal/sbi/server.go:78
  • Protected control comparison (other SMF groups DO use auth):
    • NFs/smf/internal/sbi/server.go:99
    • NFs/smf/internal/sbi/server.go:105
  • Delete handler (panic site):
    • NFs/smf/internal/sbi/api_upi.go:94
    • NFs/smf/internal/sbi/api_upi.go:99
  • AN nodes are constructed without a UPF object (root cause of the nil deref):
    • NFs/smf/internal/context/user_plane_information.go:95
    • NFs/smf/internal/context/user_plane_information.go:97

PoC

Reproduced end-to-end against the running SMF at http://10.100.200.6:8000.

  1. Control: protected sibling OAM route returns 401:
curl -i http://10.100.200.6:8000/nsmf-oam/v1/

HTTP/1.1 401 Unauthorized
  1. Trigger: unauthenticated DELETE on the default AN node gNB1:
curl -i -X DELETE http://10.100.200.6:8000/upi/v1/upNodesLinks/gNB1

HTTP/1.1 500 Internal Server Error
  1. SMF container logs (docker logs --tail 120 smf) show topology mutation landing BEFORE the panic, and the panic stack pointing at api_upi.go:99:
[INFO][SMF][Init] UPNode [gNB1] found. Deleting it.
[INFO][SMF][Init] Delete UPLink [UPF] <=> [gNB1].
[ERRO][SMF][GIN] panic: runtime error: invalid memory address or nil pointer dereference
github.com/free5gc/smf/internal/sbi.(*Server).DeleteUpNodeLink
    /go/src/free5gc/NFs/smf/internal/sbi/api_upi.go:99 +0x298
[INFO][SMF][GIN] | 500 | DELETE | /upi/v1/upNodesLinks/gNB1

The lab state was manually restored after validation by re-creating the AN entry; that POST is restoration-only and is NOT a mitigation.

Impact

Three compounding defects on the same SMF SBI surface:

  1. Missing inbound authentication (CWE-306) and authorization (CWE-862) on the UPI route group, so the trigger is reachable to any off-path network attacker who can reach SMF…
Record
GHSA-p9mg-74mg-cwwr
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-306, CWE-476, CWE-862
Updated
2026-11-02
OSVGO-2026-5537 No score

free5GC's SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating in github.com/free5gc/smf

free5GC's SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating in github.com/free5gc/smf

Record
GO-2026-5537
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/free5gc/smf
Go
 before 1.4.3
1.4.3
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-44328 is a high vulnerability (CVSS 8.2) in Free5gc, published May 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.32%, the 25th percentile. Fixed in github.com/free5gc/smf 1.4.3.

References

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