CVE-2026-4240
Open5Gs ≤ 2.7.7
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-4240 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 Exploitation for Privilege Escalation (T1068); ranked at the 42th 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 map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-4240 is a denial-of-service vulnerability affecting Open5GS versions up to and including 2.7.6. The issue resides in the CCA Handler component, specifically within the functions smf_gx_cca_cb, smf_gy_cca_cb, smf_s6b_aaa_cb, and smf_s6b_sta_cb. Manipulation of these functions leads to improper resource handling, 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 availability impact.
Any unauthenticated remote attacker can exploit this vulnerability over the network with low complexity and no user interaction required. Successful exploitation disrupts service availability on the affected Open5GS instance, potentially causing partial denial of service without impacting confidentiality or integrity.
Mitigation involves upgrading to Open5GS version 2.7.7, which addresses the issue via commit 80eb484a6ab32968e755e628b70d1a9c64f012ec. Relevant advisories and resources are available in the Open5GS GitHub repository, including the issue tracker (issues/4343) and release notes.
The exploit has been publicly disclosed and may be utilized by attackers.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12433
Vulnerability Data
A vulnerability was determined in Open5GS up to 2.7.6. The affected element is the function smf_gx_cca_cb/smf_gy_cca_cb/smf_s6b_aaa_cb/smf_s6b_sta_cb of the component CCA Handler. This manipulation causes denial of service. The attack can be initiated remotely. The exploit has been publicly disclosed and…
more
may be utilized. Upgrading to version 2.7.7 is sufficient to fix this issue. Patch name: 80eb484a6ab32968e755e628b70d1a9c64f012ec. Upgrading the affected component is recommended.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing or incorrect resource releases after code is written.
Engineering principles can require explicit resource acquisition/release patterns that stop improper shutdown from being introduced.
Priority-based resource allocation limits the blast radius when released resources are not returned to the pool.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly include coding standards for correct resource allocation and release.
Runtime monitoring can detect resource exhaustion caused by improper shutdown or release.
Lifecycle management of assets can encompass proper resource release at end-of-life or shutdown.
Capacity management helps surface leaks from unreleased resources but does not prevent the coding flaw.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Including restart, recovery and media-handling instructions reduces the likelihood that resources or sensitive data will be left in an exposed or improperly released state after a failure.