CVE-2024-39526
Juniper Junos Os Evolved 19.4 – 21.2
Raw vector
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/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:U/V:X/RE:X/U:XSummary
CVE-2024-39526 is a high-severity Improper Handling of Exceptional Conditions (CWE-755) vulnerability in Juniper Junos Os Evolved. Its CVSS base score is 7.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 30th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-24 (Fail in Known State) and SI-17 (Fail-safe Procedures) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-38052
Vulnerability Data
An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C lines cards, MX304 devices, and Juniper Networks Junos OS Evolved on PTX Series, allows an…
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attacker sending malformed DHCP packets to cause ingress packet processing to stop, leading to a Denial of Service (DoS). Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. This issue only occurs if DHCP snooping is enabled. See configuration below. This issue can be detected using following commands. Their output will display the interface status going down: user@device>show interfaces <if--x/x/x> user@device>show log messages | match <if--x/x/x> user@device>show log messages ==> will display the "[Error] Wedge-Detect : Host Loopback Wedge Detected: PFE: no," logs. This issue affects: Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C line cards, and MX304: * All versions before 21.2R3-S7, * from 21.4 before 21.4R3-S6, * from 22.2 before 22.2R3-S3, * all versions of 22.3, * from 22.4 before 22.4R3, * from 23.2 before 23.2R2; Junos OS Evolved on PTX Series: * from 19.3R1-EVO before 21.2R3-S8-EVO, * from 21.4-EVO before 21.4R3-S7-EVO, * from 22.1-EVO before 22.1R3-S6-EVO, * from 22.2-EVO before 22.2R3-S5-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R3-S1-EVO, * from 23.2-EVO before 23.2R2-S2-EVO, * from 23.4-EVO before 23.4R2-EVO. Junos OS Evolved releases prior to 19.3R1-EVO are unaffected by this vulnerability
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 1 hardening rule · 1 OS baseline
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Mitigating Controls (NIST 800-53 r5) AI
Requires the system to fail to a known safe state on specified failures, limiting the impact of unhandled exceptional conditions.
Mandates explicit fail-safe procedures triggered by indicated failures, structurally preventing unhandled or mishandled exceptional conditions.
Requires generation of appropriate error messages on exceptional conditions, directly enforcing correct handling rather than silent or incorrect behavior.
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 proper exception and error handling 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.
Security testing in development and acceptance verifies correct handling of exceptional conditions.
Documented operating procedures may specify exception handling but do not guarantee implementation.
Logging captures unhandled exceptions, aiding detection but not preventing the weakness.
Monitoring can surface unhandled exceptions but does not enforce proper handling.
Secure SDLC mandates exception-handling requirements and testing that directly prevent improper handling of exceptional conditions.
Application security requirements explicitly include handling of error and exceptional conditions.