dbcve.org
JunosOperating system · Juniper

CVE-2025-52947

MEDIUM · 6.5 CVSS v3.1 Published 2025-07-11
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
70/100
Remediation priority · Elevated
No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Improper handling of exceptional conditions in route processing on Juniper ACX Series platforms (ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, ACX5096) causes a Forwarding Engine Board crash when interface flapping occurs on the primary path port of an L2 circuit IGP while hot-standby mode is configured, resulting in DoS.

MitigationUpgrade to Junos OS 21.2R3-S9 or later; if upgrading is not feasible due to EOL status, consider network redesign to avoid hot-standby L2 circuit IGP configurations or replace with supported hardware.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:< 21.2= 21.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify ACX model
    Run 'show chassis hardware' or 'show version' to confirm the device model is one of: ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, or ACX5096
    Affected if The device model matches one of the listed ACX Series models
  2. Check Junos version
    Run 'show version' and compare the installed Junos version against the affected range: versions < 21.2 or exactly 21.2
    Affected if The installed Junos version is lower than 21.2 or equals 21.2 exactly
  3. Verify L2 circuit with IGP configuration
    Run 'show configuration protocols l2circuit' and look for neighbor statements that indicate IGP (such as interface bindings to IGP-enabled interfaces)
    Affected if An L2 circuit is configured with IGP-related settings
  4. Confirm hot-standby mode is enabled
    Run 'show configuration protocols l2circuit' and look for 'hot-standby' or 'hot-standby-mode' statements within the L2 circuit configuration
    Affected if Hot-standby mode is explicitly configured on the L2 circuit

All four conditions must be true for the device to be vulnerable: the device must be an affected ACX model, running a vulnerable Junos version (<21.2 or =21.2), with an L2 circuit using IGP, and hot-standby mode enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 21.2 or later
Fixed in 21.2
Interim mitigation

Upgrade to Junos OS 21.2R3-S9 or later; if upgrading is not feasible due to EOL status, consider network redesign to avoid hot-standby L2 circuit IGP configurations or replace with supported hardware.

Recommended fix High confidence

21.2R3-S9 or later (ensure the selected release supports the specific ACX model)

  1. 1. Identify the device model to confirm it is one of the affected ACX Series platforms: ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, or ACX5096
  2. 2. Check the current Junos OS version with command: show version
  3. 3. Verify if 'hot-standby' mode is configured for any L2 circuit using: show configuration protocols l2-circuit
  4. 4. If version is before 21.2R3-S9, download the 21.2R3-S9 or later release from the Juniper support portal
  5. 5. Plan a maintenance window as the upgrade will require a system reboot
  6. 6. Upload the new Junos OS image to the device and verify integrity
  7. 7. Perform the upgrade following standard Junos upgrade procedures
  8. 8. After reboot, verify the new version is running: show version
Caveat These are end-of-life (EOL) ACX platforms - verify Juniper support status for the target release and ensure compatibility with other network equipment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,970
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,152.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-52947 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-52947 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data