CVE-2024-39550
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 · uneditedA Missing Release of Memory after Effective Lifetime vulnerability in the rtlogd process of Juniper Networks Junos OS on MX Series with SPC3 allows an unauthenticated, adjacent attacker to trigger internal events cause ( which can be done by repeated port flaps) to cause a slow memory leak, ultimately leading to a Denial of Service (DoS). Memory can only be recovered by manually restarting rtlogd process. The memory usage can be monitored using the below command. user@host> show system processes extensive | match rtlog This issue affects Junos OS on MX Series with SPC3 line card: * from 21.2R3 before 21.2R3-S8, * from 21.4R2 before 21.4R3-S6, * from 22.1 before 22.1R3-S5, * from 22.2 before 22.2R3-S3, * from 22.3 before 22.3R3-S2, * from 22.4 before 22.4R3-S1, * from 23.2 before 23.2R2, * from 23.4 before 23.4R2.
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 confidenceA memory leak vulnerability in the rtlogd logging process on Juniper MX Series routers with SPC3 line cards allows adjacent attackers to trigger repeated internal events (port flaps) that cause memory to accumulate without release, eventually leading to process exhaustion and denial of service. Memory can only be recovered by manually restarting the rtlogd process.
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= 21.2= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2= 23.4CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Confirm hardware platform is Juniper MX Series with SPC3 line cardsRun 'show chassis hardware' or 'show chassis fpc' to identify the router model and installed line cards. Look for SPC3 (Services Processing Card 3) in the FPC (Flexible PIC Concentrator) details.Affected if The router is not an MX Series or does not have SPC3 line cards, then the vulnerability does not apply.
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Identify the installed Junos OS versionRun 'show version' to display the installed Junos version. Compare the base version number (e.g., 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, 23.2, 23.4) against the affected versions list.Affected if The installed version matches one of the affected base versions: 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, 23.2, or 23.4.
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Verify the rtlogd process is runningRun 'show system processes extensive | match rtlog' or 'ps aux | grep rtlogd' to confirm the rtlogd logging process is active on the SPC3 line card.Affected if The rtlogd process is not running, then the memory leak cannot manifest.
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Inspect rtlogd process memory consumptionRun 'show system processes extensive | match rtlog' repeatedly over time to observe memory growth. Check if the RSS (Resident Set Size) or memory utilization is continuously increasing without leveling off.Affected if Memory usage shows sustained growth and approaches system limits, indicating the leak is active.
A user is affected if they have an MX Series router with SPC3 line cards running any of the listed Junos versions and observe continuously growing memory usage in the rtlogd process.
Generated from the published advisory. Verify against your own configuration.
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 · scopedUpgrade Junos OS to one of the fixed versions (21.2R3-S8, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, 22.4R3-S1, 23.2R2, or 23.4R2 or later). Until upgraded, monitor rtlogd memory usage via 'show system processes extensive | match rtlog' and manually restart the process if memory exhaustion occurs.
Upgrade to 21.2R3-S8 / 21.4R3-S6 / 22.1R3-S5 / 22.2R3-S3 / 22.3R3-S2 / 22.4R3-S1 / 23.2R2 / 23.4R2 or later (depending on current version branch)
- 1. Identify the current Junos OS version on the MX Series device with SPC3 line card using 'show version'
- 2. Determine the appropriate upgrade path based on current version (21.2R3-S8 or later for 21.2 track, 21.4R3-S6 or later for 21.4 track, 22.1R3-S5 or later for 22.1 track, 22.2R3-S3 or later for 22.2 track, 22.3R3-S2 or later for 22.3 track, 22.4R3-S1 or later for 22.4 track, 23.2R2 or later for 23.2 track, 23.4R2 or later for 23.4 track)
- 3. Download the appropriate Junos OS upgrade image from Juniper Networks support portal
- 4. Upload the upgrade image to the device using 'file copy' or USB storage
- 5. Verify the image integrity using 'file checksum' or equivalent
- 6. Initiate the upgrade using 'request system software add <package-name>' with appropriate options (e.g., no-validate, reboot)
- 7. After upgrade completes, verify the new version with 'show version'
- 8. Confirm the rtlogd process is running normally with 'show system processes extensive | match rtlog'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-39550 in production — separate from our analysis above.
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
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