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NVD / CVE Program· CNA juniper

CVE-2025-52947: Junos OS: ACX Series: When 'hot-standby' mode is configured for an L2 circuit, interface flap causes the FEB to crash

Noroxi assessment

Priority: Monitor (action score 28/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.30% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Juniper Networks Junos OS 21.2R3-S9.

Low priority for now. Upgrade to Juniper Networks Junos OS 21.2R3-S9 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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 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.

HighCVSS 7.1 · v4.0—No exploit Fix available
Published
Jul 11, 2025
Updated
Jun 17, 2026
EPSS
0.3% · 23th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · juniper
6.5
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
juniperjunos
juniperacx1000
juniperacx1100
juniperacx2000
juniperacx2100
juniperacx2200
juniperacx4000
juniperacx5048
juniperacx5096

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • juniper junosbefore 21.2
  • juniper junos21.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (juniper). Independent of NVD's CPE analysis and usually ahead of it.

  • Juniper Networks Junos OS

    • before 21.2R3-S9affected · semver

Same product

juniper: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-36845Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variableKEV
    98Now
  • CVE-2023-36846Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesKEV
    79This week
  • CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variablesKEV
    78This week

Published before and after this one in the same product

  • ← EarlierCVE-2025-30661Jul 11, 2025 · Junos OS: Low-privileged user can cause script to run as root, leading to privilege escalation
    34Monitor
  • ← EarlierCVE-2025-52946Jul 11, 2025 · Junos OS and Junos OS Evolved: With traceoptions enabled, receipt of malformed AS PATH causes RPD crash
    34Monitor
  • Later →CVE-2025-52948Jul 11, 2025 · Junos OS: Specific unknown traffic pattern causes FPC and system to crash when packet capturing is enabled
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Juniper Networks Junos OS21.2R3-S9Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-21906188 days apartJunos OS: SRX Series: With GRE performance acceleration enabled, receipt of a specific ICMP packet causes the PFE to crash
    34Monitor
  • CVE-2024-39525275 days apartJunos OS and Junos OS Evolved: When BGP traceoptions is enabled, receipt of specially crafted BGP packet causes RPD crash
    34Monitor
  • CVE-2024-39552365 days apartJunos OS and Junos OS Evolved: Malformed BGP UPDATE causes RPD crash
    34Monitor
  • CVE-2024-39555366 days apartJunos OS and Junos OS Evolved: Receipt of a specific malformed BGP update causes the session to reset
    34Monitor
  • CVE-2024-30382455 days apartJunos OS and Junos OS Evolved: RPD crash when CoS-based forwarding (CBF) policy is configured
    34Monitor
  • CVE-2025-529480 days apartJunos OS: Specific unknown traffic pattern causes FPC and system to crash when packet capturing is enabled
    32Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-755 · Improper Handling of Exceptional Conditions

CVSS vector

CVSS: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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records