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Junos Os EvolvedOperating system · Juniper

CVE-2023-36833

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
A Use After Free vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS Evolved on PTX10001-36MR, and PTX10004, PTX10008, PTX10016 with LC1201/1202 allows an adjacent, unauthenticated attacker to cause a Denial of Service (DoS). The process 'aftman-bt' will crash after multiple flaps on a multicast-only fast reroute (MoFRR) enabled interface. This will cause the respective FPC to stop forwarding traffic and it needs to be rebooted to restore the service. An indication that the system experienced this issue is the following log message:   <date> <hostname> evo-aftmand-bt[<pid>]: [Error] jexpr_fdb: sanity check failed, ... , app_name L3 Mcast Routes This issue affects Juniper Networks Junos OS Evolved on PTX10001-36MR, PTX10004, PTX10008, PTX10016 with LC1201/1202: 21.2 version 21.2R1-EVO and later versions; 21.3 version 21.3R1-EVO and later versions; 21.4 versions prior to 21.4R3-S3-EVO; 22.1 version 22.1R1-EVO and later versions; 22.2 versions prior to 22.2R3-S2-EVO; 22.3 versions prior to 22.3R3-EVO; 22.4 versions prior to 22.4R1-S2-EVO, 22.4R2-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

Use After Free vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS Evolved on specific PTX platforms (PTX10001-36MR, PTX10004, PTX10008, PTX10016 with LC1201/1202 line cards). The vulnerability is triggered by multiple interface flaps on MoFRR-enabled interfaces, causing the 'aftman-bt' process to crash and the FPC to stop forwarding traffic.

MitigationUpgrade Junos OS Evolved to a patched version (21.4R3-S3-EVO, 22.2R3-S2-EVO, 22.3R3-EVO, 22.4R1-S2-EVO, or 22.4R2-EVO or later) on affected devices. Consider disabling MoFRR on multicast interfaces as a temporary workaround 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
Junos Os EvolvedOperating system
Affected:= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4

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 hardware model
    Run 'show chassis hardware' or 'show system hardware' to confirm the device is a PTX10001-36MR, PTX10004, PTX10008, or PTX10016, and verify it uses LC1201 or LC1202 line cards with 'show chassis fpc'
    Affected if Device is a listed PTX platform with LC1201/1202 line cards
  2. Check Junos OS Evolved version
    Run 'show version invoke-on all-routing-engines' and examine the 'Junos OS Evolved' version number
    Affected if Version equals 21.2, 21.3, 21.4, 22.1, 22.2, 22.3, or 22.4 (exact match)
  3. Determine if MoFRR is enabled
    Run 'show configuration protocols multicast-snooping' and look for 'mofrr' or 'multicast fast-reroute' statements; also run 'show multicast route extensive' and inspect for MoFRR-related interface flags
    Affected if MoFRR is configured and active on any multicast interface
  4. Check for aftman-bt process crashes
    Run 'show system core-dumps' or 'show system crash' and look for any crash files related to the 'aftman-bt' process
    Affected if Recent aftman-bt crash files exist in the system
  5. Verify FPC forwarding status
    Run 'show chassis fpc' and check the 'State' column for the FPC hosting LC1201/1202; look for 'Online' vs 'Offline' or 'Present' status
    Affected if FPC is offline or showing as not forwarding despite being physically present

You are affected if you run a vulnerable PTX platform with LC1201/1202 line cards, on an affected Junos OS Evolved version, with MoFRR enabled on multicast interfaces, or if you have documented aftman-bt crashes.

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 (21.4R3-S3-EVO, 22.2R3-S2-EVO, 22.3R3-EVO, 22.4R1-S2-EVO, or 22.4R2-EVO or later) on affected devices. Consider disabling MoFRR on multicast interfaces as a temporary workaround if upgrade is not immediately feasible.

Recommended fix High confidence

21.4R3-S3-EVO, 22.2R3-S2-EVO, 22.3R3-EVO, 22.4R1-S2-EVO, or 22.4R2-EVO (depending on which major version branch you are on)

  1. 1. Identify the current Junos OS Evolved version running on the affected PTX devices (PTX10001-36MR, PTX10004, PTX10008, PTX10016 with LC1201/1202) using 'show version' command
  2. 2. If running 21.2.x or 21.3.x, upgrade to 21.4R3-S3-EVO or later
  3. 3. If running 21.4.x, upgrade to 21.4R3-S3-EVO or later (if not already at that version)
  4. 4. If running 22.1.x, upgrade to 22.2R3-S2-EVO or later, or 22.3R3-EVO or later, or 22.4R1-S2-EVO or later, or 22.4R2-EVO or later
  5. 5. If running 22.2.x, upgrade to 22.2R3-S2-EVO or later
  6. 6. If running 22.3.x, upgrade to 22.3R3-EVO or later
  7. 7. If running 22.4.x, upgrade to 22.4R1-S2-EVO or 22.4R2-EVO or later
  8. 8. After upgrade, verify the 'aftman-bt' process stability using 'show system processes extensive | match aftman-bt'
Caveat Upgrade should follow Junos OS Evolved standard upgrade procedures; ensure proper configuration backup and planned maintenance window as FPC reboot may be required during upgrade

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
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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

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Peer-ranked notes from engineers who’ve handled CVE-2023-36833 in production — separate from our analysis above.

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