CVE-2026-1683
Published: 30 January 2026
Summary
CVE-2026-1683 is a medium-severity Improper Resource Shutdown or Release (CWE-404) vulnerability in Free5Gc Free5Gc. Its CVSS base score is 5.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 24.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-1683 is a denial-of-service vulnerability affecting Free5GC SMF versions up to 4.1.0. The issue resides in the HandlePfcpSessionReportRequest function within the file internal/pfcp/handler/handler.go of the PFCP component. Manipulation of this function can trigger a denial of service, as classified under CWE-404 (Improper Resource Shutdown or Release). The vulnerability carries a CVSS v3.1 base score of 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L), indicating medium severity with low impact on availability but no effects on confidentiality or integrity.
Any remote attacker can exploit this vulnerability without authentication or user interaction, given its network accessibility and low complexity. Successful exploitation leads to a denial of service on the affected SMF instance, potentially disrupting PFCP session reporting and related 5G core network functions.
Advisories recommend deploying a patch to mitigate the issue, with a fix available via GitHub pull request #188 in the free5gc/smf repository. Details and discussion are documented in free5gc/free5gc GitHub issue #804, including exploit disclosure to the public.
The exploit has been publicly disclosed, increasing the risk of active exploitation against unpatched Free5GC SMF deployments.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5031
Vulnerability details
A vulnerability has been found in Free5GC SMF up to 4.1.0. Affected by this vulnerability is the function HandlePfcpSessionReportRequest of the file internal/pfcp/handler/handler.go of the component PFCP. The manipulation leads to denial of service. Remote exploitation of the attack is…
more
possible. The exploit has been disclosed to the public and may be used. To fix this issue, it is recommended to deploy a patch.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE directly describes a remotely exploitable flaw in a network service that crashes the target process (SMF/PFCP handler), matching Application or System Exploitation for Endpoint DoS.
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires mechanisms to protect against or limit the effects of denial-of-service attacks targeting the PFCP handler in SMF.
Mandates timely installation of patches to remediate the known flaw in HandlePfcpSessionReportRequest before exploitation occurs.
Requires monitoring of network traffic and system behavior to identify anomalous PFCP session report requests that could trigger the DoS condition.