CVE-2026-33803
Juniper Junos Os Evolved ≤ 23.2
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/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:U/V:X/RE:M/U:XSummary
CVE-2026-33803 is a medium-severity Improper Restriction of Communication Channel to Intended Endpoints (CWE-923) vulnerability in Juniper Junos Os Evolved. Its CVSS base score is 6.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 17th 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 CM-7 (Least Functionality) and SC-7 (Boundary Protection) — 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 Restriction of Communication Channel to Intended Endpoints vulnerability in Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to cause a limited information disclosure and availability impact to the device. Due to a wrong initialization, a process…
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which should only be able to communicate internally within the device can be reached over the network via an open port. This leads to a device being inadvertently exposed and increased CPU cycles spent processing ingress packets. This issue affects Junos OS Evolved: * all versions before 23.2R2-S7-EVO, * 23.4 versions before 23.4R2-S8-EVO, * 24.2 versions before 24.2R2-S5-EVO, * 24.4 versions before 24.4R2-S4-EVO, * 25.2 versions before 25.2R2-S1-EVO, * 25.4 versions before 25.4R1-S2-EVO.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability allows unauthenticated network-based access to an internal process via an exposed port, directly enabling exploitation of a public-facing application (T1190).
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Boundary Protection directly blocks the unintended network exposure of an internal-only process by enforcing ingress/egress filtering at network boundaries.
Least Functionality prevents the erroneous binding of an internal process to a network port, ensuring only required network services are enabled.
System Monitoring can detect anomalous traffic or CPU usage caused by the unintended network-accessible process, enabling early identification of the exposure.
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.
Network segmentation and access controls directly enforce communication only with intended endpoints.
Authenticating services/hardware directly prevents communication with unintended endpoints.
Data-in-transit protections commonly include certificate-based endpoint authentication to ensure correct peers.
Documenting authorized flows helps define intended endpoints but does not enforce channel restrictions at runtime.
Protecting identity assertions supports endpoint verification but is narrower than channel restriction.
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.
Secure authentication mechanisms ensure the product communicates only with intended, authenticated endpoints.
Network security controls directly enforce endpoint validation and channel restrictions.
Security of network services includes authentication of endpoints and service-to-service channel protection.
Network segregation reduces exposure but does not itself validate specific endpoints.
Cryptography can protect channels but does not guarantee correct endpoint identity without additional controls.
Application security requirements may specify endpoint validation but do not implement it.