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JunosOperating system · Juniper

CVE-2024-39558

MEDIUM · 6.5 CVSS v3.1 Published 2024-07-10
Fix available
A fix is available. Upgrade to 20.4 / 21.3 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 Unchecked Return Value vulnerability in the Routing Protocol Daemon (rpd) on Juniper Networks Junos OS and Juniper Networks Junos OS Evolved allows a logically adjacent, unauthenticated attacker sending a specific PIM packet to cause rpd to crash and restart, resulting in a Denial of Service (DoS), when PIM is configured with Multicast-only Fast Reroute (MoFRR). Continued receipt and processing of this packet may create a sustained Denial of Service (DoS) condition. This issue is observed on Junos and Junos Evolved platforms where PIM is configured along with MoFRR. MoFRR tries to select the active path, but due to an internal timing issue, rpd is unable to select the forwarding next-hop towards the source, resulting in an rpd crash. This issue affects: Junos OS: * All versions before 20.4R3-S10, * from 21.2 before 21.2R3-S7, * from 21.4 before 21.4R3-S6, * from 22.1 before 22.1R3-S5, * from 22.2 before 22.2R3-S3, * from 22.3 before 22.3R3, * from 22.4 before 22.4R2;  Junos OS Evolved: * All versions before 20.4R3-S10 -EVO, * All versions of 21.2-EVO, * from 21.4-EVO before 21.4R3-S9-EVO, * from 22.1-EVO before 22.1R3-S5-EVO, * from 22.2-EVO before 22.2R3-S3-EVO, * from 22.3-EVO before 22.3R3-EVO, * from 22.4-EVO before 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

An unchecked return value vulnerability exists in the Routing Protocol Daemon (rpd) when processing PIM packets with Multicast-only Fast Reroute (MoFRR) enabled. An adjacent, unauthenticated attacker sending a specific PIM packet triggers an internal timing issue where rpd fails to select the forwarding next-hop toward the source, causing rpd to crash and restart. Repeated exploitation creates a sustained DoS condition.

MitigationUpgrade Junos OS/Evolved to the fixed versions specified in the advisory. If immediate upgrade is not feasible, consider disabling MoFRR or implementing network segmentation to limit logical adjacency to trusted devices.

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:< 20.4= 20.4= 21.2= 21.4= 22.1= 22.2= 22.3= 22.4
Junos Os EvolvedOperating system
Affected:< 20.4>= 21.2, < 21.3= 20.4= 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 the Junos product and version
    Run 'show version' on the device CLI to obtain the exact Junos or Junos Os Evolved version number
    Affected if The installed version matches one of the affected versions: < 20.4, = 20.4, = 21.2, = 21.4, = 22.1, = 22.2, = 22.3, = 22.4 (for Junos) or < 20.4, >= 21.2 < 21.3, = 20.4, = 21.4, = 22.1, = 22.2, = 22.3, = 22.4 (for Junos Evolved)
  2. Confirm PIM is enabled
    Run 'show protocols pim' or check the configuration under 'protocols pim' in the device config
    Affected if PIM (Protocol Independent Multicast) protocol is configured and active on the device
  3. Verify MoFRR is configured
    Run 'show multicast routing multicast-only-fast-reroute' or check configuration for 'multicast-only-fast-reroute' under the multicast routing hierarchy
    Affected if Multicast-only Fast Reroute (MoFRR) is explicitly enabled in the multicast configuration

A device is affected if it runs a vulnerable Junos version AND has both PIM and MoFRR enabled, allowing a remote adjacent attacker to trigger rpd crashes via specially crafted PIM packets.

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 20.4 / 21.3 or later
Fixed in 20.421.3
Interim mitigation

Upgrade Junos OS/Evolved to the fixed versions specified in the advisory. If immediate upgrade is not feasible, consider disabling MoFRR or implementing network segmentation to limit logical adjacency to trusted devices.

Recommended fix High confidence

Upgrade to the nearest fixed release in your current branch: Junos OS 20.4R3-S10, 21.2R3-S7, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3, or 22.4R2; Junos OS Evolved 20.4R3-S10-EVO, 21.4R3-S9-EVO, 22.1R3-S5-EVO, 22.2R3-S3-EVO, 22.3R3-EVO, or 22.4R2-EVO

  1. 1. Identify current Junos OS or Junos OS Evolved version using 'show version' command
  2. 2. Confirm PIM is configured with MoFRR using 'show configuration protocols pim' and looking for 'multicast-only-fast-reroute'
  3. 3. Schedule a maintenance window as upgrade will require system restart
  4. 4. For Junos OS: upgrade to 20.4R3-S10, 21.2R3-S7, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3, or 22.4R2 depending on your current branch
  5. 5. For Junos OS Evolved: upgrade to 20.4R3-S10-EVO, 21.4R3-S9-EVO, 22.1R3-S5-EVO, 22.2R3-S3-EVO, 22.3R3-EVO, or 22.4R2-EVO depending on your current branch
  6. 6. After upgrade, verify rpd process is running using 'show system processes routing-daemon'
  7. 7. Confirm PIM and MoFRR functionality using 'show pim neighbors' and 'show pim interfaces'
  8. 8. Monitor system logs for any rpd crashes using 'show log messages | match rpd'
Caveat Standard Junos upgrade risks apply: review release notes for any changes to PIM, MoFRR, or routing behavior; test in lab first if possible

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

Fix this in Junos Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,580
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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-2024-39558 in production — separate from our analysis above.

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