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Description

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.

PUBLISHED Reserved 2026-05-05 | Published 2026-05-27 | Updated 2026-05-27 | Assigner GitHub_M




HIGH: 8.2CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Problem types

CWE-306: Missing Authentication for Critical Function

CWE-476: NULL Pointer Dereference

CWE-862: Missing Authorization

Product status

< 4.2.2
affected

References

github.com/...ree5gc/security/advisories/GHSA-p9mg-74mg-cwwr exploit

github.com/free5gc/free5gc/issues/905 exploit

github.com/...ree5gc/security/advisories/GHSA-p9mg-74mg-cwwr

github.com/free5gc/free5gc/issues/905

github.com/free5gc/smf/pull/199

github.com/...ommit/b57bc48081c3d3a2f333d02eb78e4fd31a120deb

cve.org (CVE-2026-44328)

nvd.nist.gov (CVE-2026-44328)

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