CVE-2026-1521
Published: 28 January 2026
Summary
CVE-2026-1521 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 44.8th 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 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-1521 is a denial-of-service vulnerability (CWE-404) discovered in Open5GS versions up to and including 2.7.6. The flaw resides in the SGWC component, specifically within the function sgwc_s5c_handle_bearer_resource_failure_indication located in the file src/sgwc/s5c-handler.c. Published on 2026-01-28, it 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.
An unauthenticated remote attacker can exploit this vulnerability by manipulating the affected function, leading to a denial of service. The attack requires low complexity and no user interaction, making it accessible over the network without privileges. A public exploit has been released, increasing the risk of real-world attacks against exposed Open5GS SGWC instances.
Mitigation is addressed via a patch in commit 69b53add90a9479d7960b822fc60601d659c328b, available in the Open5GS GitHub repository. The issue was tracked in GitHub issue #4268, and practitioners should update to a patched version of Open5GS to resolve the vulnerability.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-4885
Vulnerability details
A security flaw has been discovered in Open5GS up to 2.7.6. This affects the function sgwc_s5c_handle_bearer_resource_failure_indication of the file src/sgwc/s5c-handler.c of the component SGWC. Performing a manipulation results in denial of service. The attack can be initiated remotely. The exploit…
more
has been released to the public and may be used for attacks. The patch is named 69b53add90a9479d7960b822fc60601d659c328b. It is recommended to apply a patch to fix this issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated exploitation of the SGWC handler flaw directly enables application/system crash for denial of service (T1499.004).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires applying the vendor patch (commit 69b53add) that corrects the flawed sgwc_s5c_handle_bearer_resource_failure_indication handler.
Mandates validation of all inputs to the affected SGWC function, blocking the unauthenticated manipulation that triggers the DoS.
Requires technical controls that limit the availability impact of resource-exhaustion attacks against the SGWC component.