Cyber Resilience

CVE-2025-52949

Juniper Junos ≤ 21.4

Published
11 July 2025
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v4 7.1
Click a component to see what it means
Raw vectorCVSS: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:Y/R:A/V:C/RE:M/U:Amber
EPSS Score 0.0026 18th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2025-52949 is a high-severity Improper Handling of Length Parameter Inconsistency (CWE-130) vulnerability in Juniper Junos. Its CVSS base score is 7.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 18th 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 SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

An Improper Handling of Length Parameter Inconsistency vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a logically adjacent BGP peer sending a specifically malformed BGP packet to cause rpd to crash…

more

and restart, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. Only systems configured for Ethernet Virtual Private Networking (EVPN) signaling are vulnerable to this issue. This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability.This issue affects: Junos OS: * all versions before 21.4R3-S11, * from 22.2 before 22.2R3-S7, * from 22.4 before 22.4R3-S7, * from 23.2 before 23.2R2-S4, * from 23.4 before 23.4R2-S5, * from 24.2 before 24.2R2-S1, * from 24.4 before 24.4R1-S3, 24.4R2; Junos OS Evolved: * all versions before 22.2R3-S7-EVO, * from 22.4-EVO before 22.4R3-S7-EVO, * from 23.2-EVO before 23.2R2-S4-EVO, * from 23.4-EVO before 23.4R2-S5-EVO, * from 24.2-EVO before 24.2R2-S1-EVO, * from 24.4-EVO before 24.4R1-S3-EVO, 24.4R2-EVO.

CWE(s)
CWE-130

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-28964Same product: Juniper Junos
CVE-2023-44204Same product: Juniper Junos
CVE-2024-30386Same product: Juniper Junos
CVE-2023-0026Same product: Juniper Junos
CVE-2024-30395Same product: Juniper Junos
CVE-2026-21921Same product: Juniper Junos
CVE-2026-33797Same product: Juniper Junos
CVE-2025-30646Same product: Juniper Junos
CVE-2024-39543Same product: Juniper Junos
CVE-2025-30648Same product: Juniper Junos

Affected Assets

juniper
junos
21.4, 22.2, 22.4, 23.2, 23.4 · ≤ 21.4
juniper
junos os evolved
22.2, 22.4, 23.2, 23.4, 24.2 · ≤ 22.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V3.5.5
  • V4.2.1
  • V4.2.2

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover length-parameter inconsistencies through targeted parsing tests.

SI-10 Information Input Validation good match

Input validation enforces correct length-to-data consistency checks on parsed messages before processing.

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.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly enforce length validation and input sanitization during coding and review.

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.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect length-inconsistency vulnerabilities before deployment.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and length checks that directly address inconsistent length fields.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit rules for handling message lengths and data structures.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles require robust parsing and bounds checking to prevent length-related flaws.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prohibit improper length handling and enforce defensive parsing practices.

References