dbcve.org
JunosOperating system · Juniper

CVE-2023-36834

MEDIUM · 6.5 CVSS v3.1 Published 2023-07-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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 Incomplete Internal State Distinction vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX 4600 and SRX 5000 Series allows an adjacent attacker to cause a Denial of Service (DoS). If an SRX is configured in L2 transparent mode the receipt of a specific genuine packet can cause a single Packet Processing Engines (PPE) component of the PFE to run into a loop, which in turn will render the PPE unavailable. Each packet will cause one PPE to get into a loop, leading to a gradual performance degradation until all PPEs are unavailable and all traffic processing stops. To recover the affected FPC need to be restarted. This issue affects Juniper Networks Junos OS on SRX 4600 and SRX 5000 Series: 20.1 version 20.1R1 and later versions; 20.2 versions prior to 20.2R3-S7; 20.3 version 20.3R1 and later versions; 20.4 versions prior to 20.4R3-S7; 21.1 versions prior to 21.1R3-S5; 21.2 versions prior to 21.2R3-S3; 21.3 versions prior to 21.3R3-S3; 21.4 versions prior to 21.4R3-S1; 22.1 versions prior to 22.1R3; 22.2 versions prior to 22.2R2; 22.3 versions prior to 22.3R1-S1, 22.3R2.

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

An incomplete internal state distinction in the packet forwarding engine (PFE) of Juniper SRX 4600 and SRX 5000 Series allows an adjacent attacker to cause denial of service. In L2 transparent mode, a specific genuine packet triggers a loop in one Packet Processing Engine (PPE), rendering it unavailable. Repeated packets progressively affect additional PPEs until all become unavailable, halting all traffic processing.

MitigationUpgrade Junos OS to a patched version (20.2R3-S7, 20.4R3-S7, 21.1R3-S5, 21.2R3-S3, 21.3R3-S3, 21.4R3-S1, 22.1R3, 22.2R2, or 22.3R2+). Consider disabling L2 transparent mode if upgrade is not immediately feasible.

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:= 20.1= 20.2= 20.3= 20.4= 21.1= 21.2= 21.3= 21.4

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
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 device model
    Run 'show chassis hardware' or check physical device labeling to confirm it is an SRX 4600 or SRX 5000 Series firewall
    Affected if Device is not an SRX 4600 or SRX 5000 Series (other models are not affected by this CVE)
  2. Check Junos OS version
    Run 'show version' and note the Junos OS version number
    Affected if Version matches 20.1, 20.2, 20.3, 20.4, 21.1, 21.2, 21.3, or 21.4 exactly (these are the affected versions per the CVE)
  3. Verify L2 transparent mode is enabled
    Run 'show configuration logical-systems' and 'show configuration protocols layer2' or check the forwarding options configuration with 'show configuration forwarding-options'
    Affected if L2 transparent mode is enabled on the device (this mode must be active for the vulnerability to be exploitable)
  4. Monitor PPE availability
    Run 'show chassis fpc pic-status' or 'show pfe statistics traffic' repeatedly to check for PPEs becoming unavailable or entering error states
    Affected if One or more PPEs show as offline, unavailable, or exhibit high loop counters without hardware fault explanation

Device is affected if it is an SRX 4600 or SRX 5000 Series running a listed affected Junos version AND L2 transparent mode is enabled, with PPEs becoming unavailable over time.

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 to a patched version (20.2R3-S7, 20.4R3-S7, 21.1R3-S5, 21.2R3-S3, 21.3R3-S3, 21.4R3-S1, 22.1R3, 22.2R2, or 22.3R2+). Consider disabling L2 transparent mode if upgrade is not immediately feasible.

Recommended fix High confidence

20.2R3-S7, 20.4R3-S7, or 21.x/22.x branch to latest stable release per your current version

  1. 1. Identify the current Junos OS version on the SRX 4600 or SRX 5000 Series device using 'show version'
  2. 2. If running 20.1x, upgrade to 20.2R3-S7 or later stable release (20.2R3-S7 or higher)
  3. 3. If running 20.2x versions prior to 20.2R3-S7, upgrade to 20.2R3-S7 or later
  4. 4. If running 20.3x, upgrade to 20.4R3-S7 or later stable release
  5. 5. If running 20.4x versions prior to 20.4R3-S7, upgrade to 20.4R3-S7 or later
  6. 6. For 21.1-21.4, 22.1-22.3 branches, upgrade to the minimum fixed version for your branch as listed: 21.1R3-S5, 21.2R3-S3, 21.3R3-S3, 21.4R3-S1, 22.1R3, 22.2R2, or 22.3R2
  7. 7. After upgrade, restart the FPC using 'request chassis fpc restart <slot-number>' to clear any stuck PPE state
  8. 8. Verify normal operation with 'show chassis fpc' and 'show pfe statistics'
Caveat Review Junos OS upgrade guide for your hardware platform; ensure compatibility with other deployed Juniper devices in the network

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

Fix this in Junos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-36834 — 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-2023-36834 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