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JunosOperating system · Juniper

CVE-2024-39536

MEDIUM · 5.3 CVSS v3.1 Published 2024-07-11
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
58/100
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 Missing Release of Memory after Effective Lifetime vulnerability in the Periodic Packet Management Daemon (ppmd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a Denial-of-Service (DoS). When a BFD session configured with authentication flaps, ppmd memory can leak. Whether the leak happens depends on a race condition which is outside the attackers control. This issue only affects BFD operating in distributed aka delegated (which is the default behavior) or inline mode. Whether the leak occurs can be monitored with the following CLI command: > show ppm request-queue FPC     Pending-request fpc0                   2 request-total-pending: 2 where a continuously increasing number of pending requests is indicative of the leak.  This issue affects: Junos OS: * All versions before 21.2R3-S8, * 21.4 versions before 21.4R3-S7, * 22.1 versions before 22.1R3-S4, * 22.2 versions before 22.2R3-S4, * 22.3 versions before 22.3R3, * 22.4 versions before 22.4R2-S2, 22.4R3. Junos OS Evolved: * All versions before 21.2R3-S8-EVO, * 21.4-EVO versions before 21.4R3-S7-EVO, * 22.2-EVO versions before 22.2R3-S4-EVO, * 22.3-EVO versions before 22.3R3-EVO, * 22.4-EVO versions before 22.4R3-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 memory leak vulnerability in the Periodic Packet Management Daemon (ppmd) of Juniper Junos OS allows an unauthenticated adjacent attacker to cause Denial of Service. The leak occurs when a BFD session configured with authentication flaps, operating in distributed (default) or inline mode. The leak depends on a race condition outside attacker control, causing gradual memory exhaustion.

MitigationApply the vendor-supplied patches for Junos OS and Junos OS Evolved corresponding to the affected version branches. Monitor ppm request-queue for continuously increasing pending requests as an indicator of the leak.

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:< 21.2= 21.4= 22.1= 22.2= 22.3= 22.4
Junos Os EvolvedOperating system
Affected:< 21.2= 21.2= 21.4= 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
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. Check Junos OS version
    Run 'show version' or 'show version detail' on the device
    Affected if The running version is < 21.2, or equals 21.4, 22.1, 22.2, 22.3, or 22.4 for Junos; or < 21.2, equals 21.2, 21.4, 22.2, 22.3, or 22.4 for Junos OS Evolved
  2. Verify BFD protocol is configured
    Run 'show configuration protocols bfd' to see if BFD is configured
    Affected if BFD protocol is configured on the device
  3. Confirm BFD uses authentication
    In BFD configuration, look for 'authentication' keyword (keychain, md5, sha1) under the BFD session configuration
    Affected if A BFD session is configured with any form of authentication (keychain, md5, sha1, etc.)
  4. Check BFD session mode
    Run 'show bfd session detail' and look for 'distributed' or 'inline' mode in the session parameters; if not explicitly set, distributed is the default
    Affected if BFD sessions are operating in distributed mode (default) or inline mode
  5. Monitor ppmd request queue growth
    Run 'show ppm request-queue' repeatedly over time and observe if pending requests continuously increase
    Affected if The pending request count shows sustained growth over multiple checks, indicating the memory leak

You are affected if running a vulnerable Junos version AND have BFD sessions configured with authentication operating in distributed or inline mode, with observable growth in the ppmd request queue.

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 21.2 or later
Fixed in 21.2
Interim mitigation

Apply the vendor-supplied patches for Junos OS and Junos OS Evolved corresponding to the affected version branches. Monitor ppm request-queue for continuously increasing pending requests as an indicator of the leak.

Recommended fix High confidence

Upgrade to the minimum fixed release for your current branch: 21.2R3-S8, 21.4R3-S7, 22.1R3-S4, 22.2R3-S4, 22.3R3, or 22.4R3 (or corresponding -EVO versions for Junos OS Evolved)

  1. 1. Identify all Junos OS and Junos OS Evolved devices in the environment that may be affected by checking the current software version with 'show version'.
  2. 2. For each affected device, determine the appropriate fixed release based on the current installed version: - If running <21.2, upgrade to 21.2R3-S8 or later. - If running 21.4.x, upgrade to 21.4R3-S7 or later. - If running 22.1.x, upgrade to 22.1R3-S4 or later. - If running 22.2.x, upgrade to 22.2R3-S4 or later. - If running 22.3.x, upgrade to 22.3R3 or later. - If running 22.4.x, upgrade to 22.
  3. 3. For Junos OS Evolved devices, use the corresponding -EVO versions: 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.2R3-S4-EVO, 22.3R3-EVO, or 22.4R3-EVO.
  4. 4. Before upgrading, review the BFD configuration to understand if authentication is in use: run 'show configuration protocols bfd' and check for 'authentication' statements.
  5. 5. Schedule a maintenance window and back up the current configuration.
  6. 6. Perform the upgrade following standard Junos upgrade procedures (use 'request system software add' or equivalent).
  7. 7. After upgrade, verify the fix by monitoring 'show ppm request-queue' periodically to confirm pending requests do not continuously increase.
  8. 8. Confirm BFD sessions are operating normally post-upgrade with 'show bfd session'.
Caveat Standard Junos upgrade risks apply - ensure compatibility with other network devices and review release notes for any behavioral changes between your current and target version

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
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2024-39536 in production — separate from our analysis above.

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What this is

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