CVE-2025-15539
Published: 19 January 2026
Summary
CVE-2025-15539 is a medium-severity Improper Resource Shutdown or Release (CWE-404) vulnerability in Open5Gs Open5Gs. 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 29.2th 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 SI-2 (Flaw Remediation) and SC-5 (Denial-of-service Protection).
Deeper analysis
CVE-2025-15539 is a denial-of-service vulnerability affecting Open5GS versions up to 2.7.6. The issue resides in the sgwc_s11_handle_downlink_data_notification_ack function within the file src/sgwc/s11-handler.c of the sgwc component. It stems from CWE-404 and has 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 availability impact but no confidentiality or integrity effects.
A remote attacker can exploit this vulnerability without privileges, user interaction, or high complexity over the network. Successful exploitation triggers a denial of service, disrupting the sgwc component's functionality. The exploit has been publicly disclosed and may be utilized by attackers.
Mitigation is available via the patch at commit b4707272c1caf6a7d4dca905694ea55557a0545f in the Open5GS GitHub repository. Security practitioners should deploy this patch promptly, as the issue is reported as already fixed. Additional details are documented in GitHub issues #4230 and related comments, along with the VulDB entry.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3253
Vulnerability details
A vulnerability was determined in Open5GS up to 2.7.6. Impacted is the function sgwc_s11_handle_downlink_data_notification_ack of the file src/sgwc/s11-handler.c of the component sgwc. This manipulation causes denial of service. The attack can be initiated remotely. The exploit has been publicly disclosed…
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and may be utilized. Patch name: b4707272c1caf6a7d4dca905694ea55557a0545f. To fix this issue, it is recommended to deploy a patch. The issue report is flagged as already-fixed.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated exploitation of the flaw in sgwc directly causes application crash/DoS, matching T1499.004 Application or System Exploitation.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires applying the vendor patch (commit b4707272) to remediate the improper resource handling flaw in sgwc_s11_handle_downlink_data_notification_ack before exploitation occurs.
Implements protective measures (e.g., rate limiting, resource throttling) on the sgwc S11 interface to limit the availability impact of the unauthenticated remote trigger.
Enables monitoring of sgwc component behavior and S11 traffic anomalies to identify the DoS condition triggered by the malformed downlink data notification ack.