CVE-2023-36849
Juniper Junos 21.4 … 22.3
Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2023-36849 is a medium-severity Improper Check or Handling of Exceptional Conditions (CWE-703) vulnerability in Juniper Junos. Its CVSS base score is 6.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked at the 23th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-40769
Vulnerability Data
An Improper Check or Handling of Exceptional Conditions vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a Denial of Service (DoS). When a malformed…
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LLDP packet is received, l2cpd will crash and restart. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected. Continued receipt of such packets will lead to a sustained Denial of Service. This issue affects: Juniper Networks Junos OS 21.4 versions prior to 21.4R3-S3; 22.1 versions prior to 22.1R3-S3; 22.2 versions prior to 22.2R2-S1, 22.2R3; 22.3 versions prior to 22.3R2. Juniper Networks Junos OS Evolved 21.4-EVO versions prior to 21.4R3-S2-EVO; 22.1-EVO versions prior to 22.1R3-S3-EVO; 22.2-EVO versions prior to 22.2R2-S1-EVO, 22.2R3-EVO; 22.3-EVO versions prior to 22.3R2-EVO.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Implements explicit check and handling for the exceptional condition of audit logging process failure.
Establishing and monitoring system metrics with correlation and response actions helps identify and address improper handling of exceptional conditions.
Provides a defined response to detected conditions by restricting operation, ensuring exceptional conditions are handled rather than ignored or mishandled.
Contingency training equips users with defined procedures to check and respond to exceptional conditions during disruptions, reducing exploitation of mishandled errors.
Testing verifies the system's ability to detect, handle, and recover from exceptional conditions as part of the plan, reducing exploitability of improper exception handling.
Regular updates keep contingency procedures aligned with system changes, providing structured handling for exceptional conditions that would otherwise allow unmitigated exploitation.
Policy defines checks and handling for exceptional conditions arising from security incidents.
Performing IR tests ensures exceptional conditions are properly checked and handled to enable effective response.
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 explicitly require anticipating and correctly handling exceptional conditions during design and coding.
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.
Reporting of unhandled errors or exceptional conditions surfaces latent failure paths so they can be corrected before exploitation.