Cyber Resilience

CVE-2025-52947

Juniper Junos ≤ 21.2

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:X/R:A/V:X/RE:M/U:Green
EPSS Score 0.0026 17th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2025-52947 is a high-severity Improper Handling of Exceptional Conditions (CWE-755) vulnerability in Juniper Junos. 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 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 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)

A10:2025 Mishandling of Exceptional Conditions

EU & UK References

Vulnerability Data

An Improper Handling of Exceptional Conditions vulnerability in route processing of Juniper Networks Junos OS on specific end-of-life (EOL) ACX Series platforms allows an attacker to crash the Forwarding Engine Board (FEB) by flapping an interface, leading to a Denial…

more

of Service (DoS). On ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, and ACX5096 devices, FEB0 will crash when the primary path port of the L2 circuit IGP (Interior Gateway Protocol) on the local device goes down. This issue is seen only when 'hot-standby' mode is configured for the L2 circuit. This issue affects Junos OS on ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, and ACX5096: * all versions before 21.2R3-S9.

CWE(s)
CWE-755

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1489 Service Stop Impact
Adversaries may stop or disable services on a system to render those services unavailable to legitimate users.
attack.mitre.org →
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-52948Same product: Juniper Junos
CVE-2026-0203Same product: Juniper Junos
CVE-2023-22391Same product: Juniper Junos
CVE-2025-21602Same product: Juniper Junos
CVE-2024-39552Same product: Juniper Junos
CVE-2024-21585Same product: Juniper Junos
CVE-2024-39541Same product: Juniper Junos
CVE-2024-39525Same product: Juniper Junos
CVE-2024-30380Same product: Juniper Junos
CVE-2025-30652Same product: Juniper Junos

Affected Assets

juniper
junos
21.2 · ≤ 21.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 1 hardening rule · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

SC-24 Fail in Known State good match

Requires the system to fail to a known safe state on specified failures, limiting the impact of unhandled exceptional conditions.

SI-17 Fail-safe Procedures good match

Mandates explicit fail-safe procedures triggered by indicated failures, structurally preventing unhandled or mishandled exceptional conditions.

SI-11 Error Handling partial match

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.

PR.PS-06 mostly match
prevents

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.

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

Security testing in development and acceptance verifies correct handling of exceptional conditions.

A.5.37 Documented operating procedures partial match
degrades

Documented operating procedures may specify exception handling but do not guarantee implementation.

A.8.15 Logging partial match
finds

Logging captures unhandled exceptions, aiding detection but not preventing the weakness.

A.8.16 Monitoring activities partial match
finds

Monitoring can surface unhandled exceptions but does not enforce proper handling.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates exception-handling requirements and testing that directly prevent improper handling of exceptional conditions.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly include handling of error and exceptional conditions.

References