JunosOperating system · Juniper

CVE-2022-22191

MEDIUM · 6.5 CVSS v3.1 Published 2022-04-14

Fix available

A fix is available. Upgrade to 15.1 or later.

See remediation →

70/100

Remediation priority · Elevated

No privileges Zero-click

Official description

NVD · unedited

A Denial of Service (DoS) vulnerability in the processing of a flood of specific ARP traffic in Juniper Networks Junos OS on the EX4300 switch, sent from the local broadcast domain, may allow an unauthenticated network-adjacent attacker to trigger a PFEMAN watchdog timeout, causing the Packet Forwarding Engine (PFE) to crash and restart. After the restart, transit traffic will be temporarily interrupted until the PFE is reprogrammed. In a virtual chassis (VC), the impacted Flexible PIC Concentrator (FPC) may split from the VC temporarily, and join back into the VC once the PFE restarts. Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS on the EX4300: All versions prior to 15.1R7-S12; 18.4 versions prior to 18.4R2-S10, 18.4R3-S11; 19.1 versions prior to 19.1R3-S8; 19.2 versions prior to 19.2R1-S9, 19.2R3-S4; 19.3 versions prior to 19.3R3-S5; 19.4 versions prior to 19.4R2-S6, 19.4R3-S7; 20.1 versions prior to 20.1R3-S3; 20.2 versions prior to 20.2R3-S3; 20.3 versions prior to 20.3R3-S2; 20.4 versions prior to 20.4R3-S1; 21.1 versions prior to 21.1R3; 21.2 versions prior to 21.2R2-S1, 21.2R3; 21.3 versions prior to 21.3R1-S2, 21.3R2.

Technical summary

dbcve analysis · high confidence

A specific flood of ARP traffic from the local broadcast domain triggers a PFEMAN watchdog timeout on Juniper EX4300 switches, causing the Packet Forwarding Engine to crash and restart. In virtual chassis configurations, this can cause FPC to temporarily split from the VC. The sustained receipt of these packets creates a persistent DoS condition.

MitigationUpgrade Junos OS on EX4300 switches to the fixed versions specified in the advisory. Implement network segmentation or ACLs to limit ARP traffic from untrusted sources if immediate upgrade is not feasible.

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

Affected products & versions

NVD · CPE data

JunosOperating system

Affected:< 15.1= 15.1= 18.4= 19.1= 19.2= 19.3= 19.4= 20.1= 20.2= 20.3= 20.4= 21.1

CVSS breakdown

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?

dbcve checks

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

Confirm EX4300 switch model

Run 'show chassis hardware' or 'show version' to identify the device model

Affected if Device is NOT an EX4300 switch (other models are not affected by this specific CVE)
Check Junos OS version

Run 'show version' and locate the Junos OS version string

Affected if Version matches < 15.1, = 15.1, = 18.4, = 19.1, = 19.2, = 19.3, = 19.4, = 20.1, = 20.2, = 20.3, = 20.4, or = 21.1
Verify virtual chassis configuration

Run 'show virtual-chassis' to check if VC is enabled

Affected if Virtual chassis is configured (FPC split becomes possible in addition to FPC crash)
Check for recent PFEMAN restarts

Run 'show system crash' and review logs for 'pfeman' or 'FPC' restart entries

Affected if PFEMAN watchdog timeouts or FPC crashes/restarts are logged around the time of ARP traffic spikes

Environment is affected if the device is an EX4300 running a Junos version listed as vulnerable and ARP traffic flood from the local broadcast domain can reach the switch.

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

Remediation

dbcve · scoped

Upgrade available Upgrade to 15.1 or later

Fixed in 15.1

Interim mitigation

Upgrade Junos OS on EX4300 switches to the fixed versions specified in the advisory. Implement network segmentation or ACLs to limit ARP traffic from untrusted sources if immediate upgrade is not feasible.

Recommended fix High confidence

For 15.1: upgrade to 15.1R7-S12 or later; For 18.4: upgrade to 18.4R3-S11 or later; For 19.1: upgrade to 19.1R3-S8 or later; For 19.2: upgrade to 19.2R3-S4 or later; For 19.3: upgrade to 19.3R3-S5 or later; For 19.4: upgrade to 19.4R3-S7 or later; For 20.1: upgrade to 20.1R3-S3 or later; For 20.2: u

1. Run 'show version' to identify current Junos OS version installed on the EX4300 switch
2. Run 'request system software validate' with the target upgrade version to check for compatibility issues
3. Run 'request system snapshot' to backup the current configuration and software
4. Run 'request system software add <package>' to install the appropriate fixed Junos OS version for your release line
5. Run 'request system reboot' to complete the upgrade
6. After reboot, verify the new version with 'show version' and confirm PFE is operational with 'show chassis fpc pic-status'
7. In virtual chassis setups, verify all members joined back with 'show virtual-chassis'

Caveat Review Juniper release notes for your current and target version for any feature changes or migration considerations before upgrading; test in lab if possible

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

Fix this in Junos Scoped from the published advisory

Consultation4.0 h
Implementation3.0 h
Testing3.0 h
Review / QA2.0 h

12.0 hours of engineering $2,150

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Scan for this in your stack

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References

Primary sources

kb.juniper.netVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-22191 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2022-22191?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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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

At a glance

A fix existsUpgrade to 15.1 or later

Severity 6.5 Medium

Exploit likelihood EPSS, next 30 days 0.4%

Affects: Junos

Remediation

Need this fixed?

Fix this in Junos 12 hrs · Moderate

Typical engagement from $2,150

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You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

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

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References