CVE-2023-37021
Open5Gs ≤ 2.6.4
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-37021 is a high-severity Reachable Assertion (CWE-617) vulnerability in Open5Gs Open5Gs. Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked in the top 45% of CVEs by exploit likelihood; 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-2023-37021 affects Open5GS MME versions up to and including 2.6.4, where an assertion failure can be remotely triggered through a malformed ASN.1 packet over the S1AP interface. The issue arises when an attacker sends a UE Context Modification Failure message lacking the required MME_UE_S1AP_ID field, causing the MME to crash. This vulnerability, associated with CWE-617 (Reachable Assertion), was published on 2025-01-22 and carries a CVSS v3.1 base score of 8.6 (AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H), indicating high severity due to its network accessibility, low complexity, lack of privileges or user interaction, and scope change with high availability impact.
A remote, unauthenticated attacker can exploit this vulnerability by transmitting the malformed S1AP message to the targeted MME, leading to repeated crashes and denial of service. The attack requires no prior authentication or special access, as it leverages the S1AP interface typically exposed in 4G/5G core network deployments. Successful exploitation disrupts MME functionality, potentially halting user equipment context management and signaling for affected cells or networks.
Mitigation details are provided in the advisory at https://cellularsecurity.org/ransacked. Security practitioners should consult this reference for patch information, workarounds, or upgrade guidance for Open5GS MME.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-40941
Vulnerability Data
Open5GS MME version <= 2.6.4 contains an assertion that can be remotely triggered via a malformed ASN.1 packet over the S1AP interface. An attacker may send a `UE Context Modification Failure` message missing a required `MME_UE_S1AP_ID` field to repeatedly crash…
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the MME, resulting in denial of service.
- 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 finds reachable assertions during development.
Security engineering principles discourage use of assertions for handling untrusted input.
Validating untrusted inputs structurally prevents attacker data from reaching and triggering assertions.
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.
Runtime monitoring of software can detect assertion-triggered crashes as adverse events.
Vulnerability identification processes can discover and record reachable-assertion flaws before deployment.
Secure SDLC practices directly prevent unsafe assertions from being coded in reachable paths.
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.