CVE-2026-57023
Juniper Junos 23.4 … 25.2
Raw vector
CVSS:4.0/AV:N/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:Y/R:A/V:X/RE:M/U:XSummary
CVE-2026-57023 is a high-severity Improper Validation of Specified Quantity in Input (CWE-1284) vulnerability in Juniper Junos. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 26th 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-7 (Boundary Protection) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.
EU & UK References
No EU or UK CSIRT advisories indexed for this CVE.
Vulnerability Data
An Improper Validation of Specified Quantity in Input vulnerability in the TCP proxy plugin of Juniper Networks Junos OS on MX Series with SPC3, and SRX Series allows an unauthenticated, network-based attacker to cause a complete Denial of Service (DoS).…
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When TCP proxy is engaged in a flow session, to support ALGs, Advanced Anti-Malware, ICAP or UTM, a TCP packet with specifically malformed TCP header will cause flow processing daemon (flowd) to crash and restart. This causes a complete service outage until the system has automatically recovered. This issue affects Junos OS on MX with SPC3, and SRX Series: * 23.4 versions before 23.4R2-S7, * 24.2 versions before 24.2R2-S4, * 24.4 versions before 24.4R2-S3, * 25.2 versions before 25.2R2. This issue does not affect releases before 23.4R1.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Malformed TCP header in proxy flow triggers flowd crash, directly enabling application-layer DoS via crafted network traffic (T1499.004).
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Boundary protection at the network perimeter can block or rate-limit the malformed TCP packets before they reach the vulnerable TCP proxy on MX/SRX devices.
Timely application of the vendor-supplied patches (23.4R2-S7, 24.2R2-S4, etc.) directly eliminates the improper TCP-header validation flaw that triggers the flowd crash.
Continuous monitoring of flowd process health and anomalous TCP traffic patterns can detect the onset of the DoS condition and trigger alerts or automated recovery.
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 require proper quantity/length validation in input handling.
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 can detect missing quantity validation but does not itself implement the control.
Secure development lifecycle mandates input validation for quantity fields, directly preventing CWE-1284.
Application security requirements explicitly call for validation of size/length inputs, mitigating CWE-1284.
Secure architecture principles encourage robust input handling but do not specifically address quantity validation.
Secure coding standards require explicit checks on numeric quantity inputs, fully addressing CWE-1284.