CVE-2026-1586 is a vulnerability identified in Open5GS, an open-source 5G core network implementation widely used for mobile network infrastructure. The flaw exists in the SGWC (Serving Gateway Control) component, specifically within the function ogs_gtp2_f_teid_to_ip located in the /sgwc/s11-handler.c source file. This function is responsible for handling GTP (GPRS Tunneling Protocol) messages, particularly mapping TEID (Tunnel Endpoint Identifier) values to IP addresses. Due to improper handling or validation of input data, an attacker can craft malicious GTP messages that exploit this flaw to trigger a denial of service (DoS) condition, causing the SGWC process to crash or become unresponsive. The vulnerability is exploitable remotely without any authentication or user interaction, increasing its attack surface. Versions 2.7.0 through 2.7.5 of Open5GS are affected. The issue has been publicly disclosed and fixed in subsequent releases, though no active exploits have been reported in the wild. The CVSS 4.0 base score is 6.9 (medium severity), reflecting the ease of remote exploitation and the impact on availability. This vulnerability can disrupt 5G core network operations, potentially affecting mobile service continuity and reliability.

For European organizations, especially telecom operators and 5G infrastructure providers, this vulnerability poses a risk of service disruption due to denial of service attacks on the SGWC component of Open5GS. A successful attack could lead to partial or full unavailability of 5G core network functions, impacting mobile subscribers and enterprise customers relying on 5G connectivity. This can result in degraded network performance, loss of revenue, and reputational damage. Critical services dependent on 5G, such as IoT deployments, smart city applications, and emergency communications, may also be affected. Given the remote and unauthenticated nature of the exploit, attackers could launch DoS attacks from outside the network perimeter, increasing the threat level. While no known exploits are currently active, the public disclosure and availability of proof-of-concept code raise the risk of future exploitation. Organizations operating Open5GS in Europe must prioritize patching to maintain network resilience and service continuity.

1. Immediately upgrade Open5GS deployments to the latest patched version beyond 2.7.5 that addresses CVE-2026-1586. 2. Implement strict network filtering to block unauthorized or malformed GTP traffic at network boundaries, especially on interfaces exposed to untrusted networks. 3. Deploy anomaly detection systems to monitor GTP message patterns and identify suspicious TEID-to-IP mapping requests or malformed packets targeting SGWC. 4. Segment 5G core network components to limit lateral movement and isolate critical functions from general network traffic. 5. Regularly audit and update Open5GS configurations to follow security best practices, including minimizing exposed services and interfaces. 6. Establish incident response procedures specific to 5G core network disruptions to quickly identify and mitigate DoS events. 7. Collaborate with vendors and the open-source community to stay informed about emerging threats and patches related to Open5GS.