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Junos Os EvolvedOperating system · Juniper

CVE-2025-52985

MEDIUM · 5.3 CVSS v3.1 Published 2025-07-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable 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
A Use of Incorrect Operator vulnerability in the Routing Engine firewall of Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to bypass security restrictions. When a firewall filter which is applied to the lo0 or re:mgmt interface references a prefix list with 'from prefix-list', and that prefix list contains more than 10 entries, the prefix list doesn't match and packets destined to or from the local device are not filtered. This issue affects firewall filters applied to the re:mgmt interfaces as input and output, but only affects firewall filters applied to the lo0 interface as output. This issue is applicable to IPv4 and IPv6 as a prefix list can contain IPv4 and IPv6 prefixes. This issue affects Junos OS Evolved: * 23.2R2-S3-EVO versions before 23.2R2-S4-EVO, * 23.4R2-S3-EVO versions before 23.4R2-S5-EVO, * 24.2R2-EVO versions before 24.2R2-S1-EVO, * 24.4-EVO versions before 24.4R1-S3-EVO, 24.4R2-EVO. This issue doesn't affect Junos OS Evolved versions before 23.2R1-EVO.

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

In Juniper Networks Junos OS Evolved, a firewall filter applied to the loopback (lo0) or routing engine management (re:mgmt) interface that references a prefix list with 'from prefix-list' fails to match packets when that prefix list contains more than 10 entries. This allows an unauthenticated network-based attacker to bypass intended security restrictions and send unfiltered traffic to or from the local device.

MitigationUpgrade Junos OS Evolved to a patched version (23.2R2-S4-EVO, 23.4R2-S5-EVO, 24.2R2-S1-EVO, or 24.4R1-S3-EVO/24.4R2-EVO), or ensure prefix lists used in firewall filters on affected interfaces contain 10 or fewer entries.

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
Junos Os EvolvedOperating system
Affected:= 23.2= 23.4= 24.2= 24.4

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

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. Check Junos OS Evolved version
    Run 'show version' or 'show version detail' to display the installed Junos OS Evolved version
    Affected if Version displayed is 23.2, 23.4, 24.2, or 24.4 (any build in these release lines)
  2. Identify firewall filters on loopback interface
    Run 'show configuration interfaces lo0' to view any firewall filter applied to the loopback (lo0) interface
    Affected if A firewall filter is applied to lo0 interface
  3. Identify firewall filters on management interface
    Run 'show configuration interfaces re:mgmt' or 'show configuration interfaces em0' to view any firewall filter applied to the routing engine management interface
    Affected if A firewall filter is applied to re:mgmt or em0 interface
  4. Check filter uses prefix-list matching
    For each firewall filter found on lo0 or re:mgmt, run 'show configuration firewall filter <filter-name>' and inspect for 'from prefix-list' terms within filter terms
    Affected if Filter contains a 'from prefix-list' term
  5. Count prefix-list entries
    Run 'show configuration prefix-list <prefix-list-name>' for each prefix-list referenced in the filter, count the number of ip addresses listed under the prefix-list
    Affected if The prefix-list contains more than 10 entries

Environment is affected if running Junos OS Evolved 23.2, 23.4, 24.2, or 24.4 AND has a firewall filter with 'from prefix-list' applied to lo0 or re:mgmt interface AND that prefix-list contains more than 10 entries.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Junos OS Evolved to a patched version (23.2R2-S4-EVO, 23.4R2-S5-EVO, 24.2R2-S1-EVO, or 24.4R1-S3-EVO/24.4R2-EVO), or ensure prefix lists used in firewall filters on affected interfaces contain 10 or fewer entries.

Recommended fix High confidence

Upgrade to 23.2R2-S4-EVO (or later 23.2.x), 23.4R2-S5-EVO (or later 23.4.x), 24.2R2-S1-EVO (or later 24.2.x), or 24.4R2-EVO (or later 24.4.x) depending on your current branch

  1. 1. Identify the current Junos OS Evolved version using 'show version' command
  2. 2. Based on your current version branch, plan upgrade to one of the fixed releases: 23.2R2-S4-EVO, 23.4R2-S5-EVO, 24.2R2-S1-EVO, or 24.4R2-EVO
  3. 3. Download the appropriate upgrade package from Juniper Networks support portal (supportportal.juniper.net)
  4. 4. Before upgrading, backup current configuration using 'request system configuration rescue save'
  5. 5. Transfer the upgrade package to the device using FTP/SCP to /var/tmp/
  6. 6. Initiate the upgrade using 'request system software add /var/tmp/<package-name> reboot'
  7. 7. After reboot, verify the new version using 'show version'
  8. 8. Verify firewall filter functionality with prefix lists containing more than 10 entries to confirm the fix
Caveat Standard Junos OS Evolved upgrade procedures apply; ensure compatibility with existing configurations and review release notes for any behavior changes

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

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2025-52985 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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