CVE-2026-33783
Juniper Junos Os Evolved ≤ 22.4
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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:U/V:X/RE:M/U:XSummary
CVE-2026-33783 is a high-severity Function Call With Incorrect Argument Type (CWE-686) vulnerability in Juniper Junos Os Evolved. Its CVSS base score is 7.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 15th 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 AC-6 (Least Privilege) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-21201
Vulnerability Data
A Function Call With Incorrect Argument Type vulnerability in the sensor interface of Juniper Networks Junos OS Evolved on PTX Series allows a network-based, authenticated attacker with low privileges to cause a complete Denial of Service (DoS). If colored SRTE…
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policy tunnels are provisioned via PCEP, and gRPC is used to monitor traffic in these tunnels, evo-aftmand crashes and doesn't restart which leads to a complete and persistent service impact. The system has to be manually restarted to recover. The issue is seen only when the Originator ASN field in PCEP contains a value larger than 65,535 (32-bit ASN). The issue is not reproducible when SRTE policy tunnels are statically configured. This issue affects Junos OS Evolved on PTX Series: * all versions before 22.4R3-S9-EVO, * 23.2 versions before 23.2R2-S6-EVO, * 23.4 versions before 23.4R2-S7-EVO, * 24.2 versions before 24.2R2-S4-EVO, * 24.4 versions before 24.4R2-S2-EVO, * 25.2 versions before 25.2R1-S2-EVO, 25.2R2-EVO.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CWE-686 input mishandling in PCEP/gRPC sensor path directly triggers daemon crash and persistent DoS, matching Application or System Exploitation.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely patching of the flawed sensor interface code in Junos OS Evolved to eliminate the incorrect-argument crash on 32-bit ASN values.
Enforces least privilege so that low-privileged authenticated users cannot reach the gRPC/PCEP monitoring path that triggers the type-mismatch DoS.
Restricts activation of non-essential gRPC sensor monitoring for colored SRTE tunnels, removing the attack surface when PCEP with large ASNs is in use.
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 (static analysis, code review, typed APIs, testing) directly prevent incorrect-argument calls while this single weakness addresses only a narrow slice of the control's broader intent.
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 type-related defects through unit, integration, and static-analysis testing.
Secure development life cycle includes coding standards and reviews that can catch type-mismatch errors.
Application security requirements can mandate strong typing and interface contracts that prevent incorrect argument types.
Secure system architecture and engineering principles promote type-safe designs and interface definitions.
Secure coding directly addresses type safety, static analysis, and compiler warnings for argument mismatches.