dbcve.org
Junos Os EvolvedOperating system · Juniper

CVE-2026-57029

MEDIUM · 5.3 CVSS v3.1 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
58/100
Remediation priority · Elevated
No privileges Zero-click 6 weeks old

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 Missing Synchronization vulnerability in the flow collector handler of Juniper Networks Junos OS Evolved on QFX Series allows an adjacent, unauthenticated attacker to cause a Denial-of-Service (DoS). When the reachability of an sFlow collector changes, the corresponding next-hop entry is updated. If this update occurs simultaneously with the sFlow thread accessing the next-hop data (which is outside the attackers control), it causes the evo-pfemand process to crash, impacting all traffic forwarding until the automatic process restart has completed. This issue affects Junos OS Evolved on QFX Series: * all 23.2 versions,  * 23.4 versions before 23.4R2-S7-EVO, * 24.2 versions before 24.2R2-S5-EVO, * 24.4 versions before 24.4R2-S3-EVO, * 25.2 versions before 25.2R2-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 race condition vulnerability in the sFlow flow collector handler of Juniper Networks Junos OS Evolved on QFX Series allows an adjacent unauthenticated attacker to cause a DoS. When the reachability of an sFlow collector changes, the corresponding next-hop entry is updated. If this update occurs simultaneously with the sFlow thread accessing the next-hop data, it causes the evo-pfemand process to crash, impacting all traffic forwarding until automatic process restart completes.

MitigationApply the vendor-supplied patches/updates: upgrade to 23.4R2-S7-EVO or later, 24.2R2-S5-EVO or later, 24.4R2-S3-EVO or later, or 25.2R2-EVO or later. For 23.2 versions, contact Juniper for available fixes.

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= 25.2

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:H/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 device model and OS type
    Run 'show chassis hardware' or 'show system information' to confirm the device is a QFX Series running Junos OS Evolved (not standard Junos OS).
    Affected if Device is a QFX Series model running Junos OS Evolved.
  2. Check installed Junos OS Evolved version
    Run 'show version' or 'show version invoke-on all-routing-engines' to identify the exact version string installed.
    Affected if The installed version matches exactly 23.2, 23.4, 24.2, 24.4, or 25.2.
  3. Verify sFlow is enabled
    Run 'show sflow' or 'show protocol sflow' to check if sFlow sampling is configured and active on any interfaces.
    Affected if sFlow protocol is enabled and configured on the device.
  4. Check for sFlow collector configuration
    Run 'show configuration sflow' to display the sFlow collector settings, including collector IP address and UDP port.
    Affected if An sFlow collector is defined and reachable on the network.
  5. Review evo-pfemand process crash logs
    Run 'show log messages' or 'show log chassisd' and search for 'evo-pfemand' crash entries or process restart notifications, particularly noting timing around sFlow collector reachability changes.
    Affected if Recent evo-pfemand crashes or restarts are present in system logs.

A device is affected if it is a QFX Series running Junos OS Evolved version 23.2, 23.4, 24.2, 24.4, or 25.2 with sFlow enabled and an sFlow collector configured, particularly if evo-pfemand process crashes appear in logs.

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

Apply the vendor-supplied patches/updates: upgrade to 23.4R2-S7-EVO or later, 24.2R2-S5-EVO or later, 24.4R2-S3-EVO or later, or 25.2R2-EVO or later. For 23.2 versions, contact Juniper for available fixes.

Recommended fix High confidence

Upgrade to 23.4R2-S7-EVO, 24.2R2-S5-EVO, 24.4R2-S3-EVO, or 25.2R2-EVO (or later respective releases) depending on your current branch

  1. 1. Identify the current Junos OS Evolved version running on the QFX Series device using 'show version' command
  2. 2. Based on your current version branch, plan upgrade to the minimum fixed version: For 23.2 branch upgrade to 23.4R2-S7-EVO or later; For 23.4 branch upgrade to 23.4R2-S7-EVO or later; For 24.2 branch upgrade to 24.2R2-S5-EVO or later; For 24.4 branch upgrade to 24.4R2-S3-EVO or later; For 25.2 branch upgrade to 25.2R2-EVO or later
  3. 3. Download the appropriate upgrade image from the Juniper Networks support portal (supportportal.juniper.net)
  4. 4. Back up the current configuration using 'request system snapshot' or by exporting configuration
  5. 5. Upload the new Junos OS Evolved image to the device's /var/tmp directory
  6. 6. Initiate the upgrade with 'request system software add /var/tmp/<image-name>' command
  7. 7. After upgrade completes, reboot the device using 'request system reboot'
  8. 8. Verify the new version is running with 'show version' and confirm the evo-pfemand process is stable
Caveat Standard Junos OS upgrade considerations apply - brief traffic disruption during reboot; review release notes for any configuration changes

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

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2026-57029 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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