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JunosOperating system · Juniper

CVE-2025-52955

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 Incorrect Calculation of Buffer Size vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent unauthenticated attacker to cause a memory corruption that leads to a rpd crash.  When the logical interface using a routing instance flaps continuously, specific updates are sent to the jflow/sflow modules. This results in memory corruption, leading to an rpd crash and restart.  Continued receipt of these specific updates will cause a sustained Denial of Service condition. This issue affects Junos OS: * All versions before 21.2R3-S9, * All versions of 21.4, * All versions of 22.2, * from 22.4 before 22.4R3-S7, * from 23.2 before 23.2R2-S3, * from 23.4 before 23.4R2-S4, * from 24.2 before 24.2R2. Junos OS Evolved:  * All versions of 21.2-EVO,  * All versions of 21.4-EVO,  * All versions of 22.2-EVO,  * from 22.4 before 22.4R3-S7-EVO,  * from 23.2 before 23.2R2-S3-EVO,  * from 23.4 before 23.4R2-S4-EVO,  * from 24.2 before 24.2R2-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

A buffer size miscalculation in the rpd daemon causes memory corruption when a logical interface with a routing instance flaps continuously, sending specific updates to jflow/sflow modules. This leads to rpd crash and restart, with continued interface flapping resulting in sustained denial of service. The vulnerability is exploitable by adjacent unauthenticated attackers.

MitigationUpgrade Junos OS or Junos OS Evolved to the specified patched versions (22.4R3-S7, 23.2R2-S3, 23.4R2-S4, 24.2R2 or later) to resolve the buffer size calculation error in the rpd daemon.

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= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2
Junos Os EvolvedOperating system
Affected:= 21.2= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2

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 installed Junos version
    Run 'show version' or 'version' command on the device to obtain the exact Junos OS or Junos OS Evolved version
    Affected if The version matches any of the affected versions listed (21.2, 21.4, 22.2, 22.4, 23.2, 23.4, 24.2) or is earlier than 21.2
  2. Verify rpd daemon is running
    Run 'show system processes routing' or check process status to confirm the rpd routing daemon is active
    Affected if rpd is running and the version is affected
  3. Check for jflow or sflow configuration
    Run 'show configuration | match jflow' and 'show configuration | match sflow' to see if flow sampling modules are enabled
    Affected if jflow or sflow is configured on the device
  4. Identify logical interfaces with routing instances
    Run 'show configuration logical-systems' and review interface assignments under routing-instances, or use 'show interfaces terse' to list logical interfaces
    Affected if Logical interfaces are bound to non-default routing instances

The device is affected if it runs a vulnerable Junos version (21.2, 21.4, 22.2, 22.4, 23.2, 23.4, 24.2 or earlier) AND has rpd running with jflow/sflow configured on logical interfaces that participate in routing instances that can flap.

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 Junos OS or Junos OS Evolved to the specified patched versions (22.4R3-S7, 23.2R2-S3, 23.4R2-S4, 24.2R2 or later) to resolve the buffer size calculation error in the rpd daemon.

Recommended fix High confidence

Upgrade to 24.2R2 (or latest 24.2R2-x) for current branches; for 21.2 branch upgrade to 21.2R3-S9; for 22.4 branch upgrade to 22.4R3-S7; for 23.2 branch upgrade to 23.2R2-S3; for 23.4 branch upgrade to 23.4R2-S4

  1. 1. Identify the current Junos OS or Junos OS Evolved version running on the device using 'show version'
  2. 2. Determine the appropriate upgrade path based on the current major version branch
  3. 3. Download the appropriate fixed release from Juniper Networks support portal
  4. 4. Upload the Junos OS upgrade package to the device using 'file copy' or USB transfer
  5. 5. For Junos OS: Run 'request system software add <package>' to install the upgrade
  6. 6. For Junos OS Evolved: Run 'request system software evo add <package>' to install the upgrade
  7. 7. After installation, reboot the device using 'request system reboot'
  8. 8. Verify the new version is running with 'show version' and confirm the vulnerability is resolved
Caveat Minor Junos releases may include behavioral changes; ensure to review release notes for compatibility with existing configurations and connected devices before upgrading

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

Fix this in Junos Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,200
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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-2025-52955 in production — separate from our analysis above.

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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