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NVD / CVE Program· CNA juniper

CVE-2024-21587: Junos OS: MX Series: Memory leak in bbe-smgd process if BFD liveness detection for DHCP subscribers is enabled

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.27% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Juniper Networks Junos OS 20.4R3-S9, 21.2R3-S7, 21.3R3-S5.

Low priority for now. Upgrade to Juniper Networks Junos OS 20.4R3-S9, 21.2R3-S7, 21.3R3-S5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An Improper Handling of Exceptional Conditions vulnerability in the broadband edge subscriber management daemon (bbe-smgd) of Juniper Networks Junos OS on MX Series allows an attacker directly connected to the vulnerable system who repeatedly flaps DHCP subscriber sessions to cause a slow memory leak, ultimately leading to a Denial of Service (DoS). Memory can only be recovered by manually restarting bbe-smgd. This issue only occurs if BFD liveness detection for DHCP subscribers is enabled. Systems without BFD liveness detection enabled are not vulnerable to this issue. Indication of the issue can be observed by periodically executing the 'show system processes extensive' command, which will indicate an increase in memory allocation for bbe-smgd. A small amount of memory is leaked every time a DHCP subscriber logs in, which will become visible over time, ultimately leading to memory starvation. user@junos> show system processes extensive | match bbe-smgd 13071 root 24 0 415M 201M select 0 0:41 7.28% bbe-smgd{bbe-smgd} 13071 root 20 0 415M 201M select 1 0:04 0.00% bbe-smgd{bbe-smgd} ... user@junos> show system processes extensive | match bbe-smgd 13071 root 20 0 420M 208M select 0 4:33 0.10% bbe-smgd{bbe-smgd} 13071 root 20 0 420M 208M select 0 0:12 0.00% bbe-smgd{bbe-smgd} ... This issue affects Juniper Networks Junos OS on MX Series: * All versions earlier than 20.4R3-S9; * 21.2 versions earlier than 21.2R3-S7; * 21.3 versions earlier than 21.3R3-S5; * 21.4 versions earlier than 21.4R3-S5; * 22.1 versions earlier than 22.1R3-S4; * 22.2 versions earlier than 22.2R3-S3; * 22.3 versions earlier than 22.3R3-S2; * 22.4 versions earlier than 22.4R2-S2, 22.4R3; * 23.2 versions earlier than 23.2R1-S1, 23.2R2.

MediumCVSS 6.5 · v3.1—No exploit Fix available
Published
Jan 11, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 20th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
6.5
CNA · juniper
6.5
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2024-21587

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
juniperjunos
junipermx10
junipermx10000
junipermx10003
junipermx10004
junipermx10008
junipermx10016
junipermx104
junipermx150
junipermx2008
junipermx2010
junipermx2020

and 8 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • juniper junos20.4
  • juniper junos21.2
  • juniper junos21.3
  • juniper junos21.4
  • juniper junos22.1
  • juniper junos22.2
  • juniper junos22.3
  • juniper junos22.4
  • juniper junos23.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (juniper). Independent of NVD's CPE analysis and usually ahead of it.

  • Juniper Networks Junos OS

    • before 20.4R3-S9affected · semver
    • 21.2 and later · before 21.2R3-S7affected · semver
    • 21.3 and later · before 21.3R3-S5affected · semver
    • 21.4 and later · before 21.4R3-S5affected · semver
    • 22.1 and later · before 22.1R3-S4affected · semver
    • 22.2 and later · before 22.2R3-S3affected · semver
    • 22.3 and later · before 22.3R3-S2affected · semver
    • 22.4 and later · before 22.4R2-S2, 22.4R3affected · semver
    • 23.2 and later · before 23.2R1-S1, 23.2R2affected · semver

Same product

juniper: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-36845Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variableKEV
    98Now
  • CVE-2023-36846Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesKEV
    79This week
  • CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variablesKEV
    78This week

Published before and after this one in the same product

  • ← EarlierCVE-2023-36842Jan 11, 2024 · Junos OS: jdhcpd will hang on receiving a specific DHCP packet
    26Monitor
  • ← EarlierCVE-2024-21585Jan 11, 2024 · Junos OS and Junos OS Evolved: BGP session flaps on NSR-enabled devices can cause rpd crash
    23Monitor
  • Later →CVE-2024-21591Jan 11, 2024 · Junos OS: SRX Series and EX Series: Security Vulnerability in J-web allows a preAuth Remote Code Execution
    44Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Juniper Networks Junos OS20.4R3-S9Vendor (CNA)
Juniper Networks Junos OS21.2R3-S7Vendor (CNA)
Juniper Networks Junos OS21.3R3-S5Vendor (CNA)
Juniper Networks Junos OS21.4R3-S5Vendor (CNA)
Juniper Networks Junos OS22.1R3-S4Vendor (CNA)
Juniper Networks Junos OS22.2R3-S3Vendor (CNA)
Juniper Networks Junos OS22.3R3-S2Vendor (CNA)
Juniper Networks Junos OS22.4R2-S2, 22.4R3Vendor (CNA)
Juniper Networks Junos OS23.2R1-S1, 23.2R2Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2024-3038292 days apartJunos OS and Junos OS Evolved: RPD crash when CoS-based forwarding (CBF) policy is configured
    34Monitor
  • CVE-2024-39555181 days apartJunos OS and Junos OS Evolved: Receipt of a specific malformed BGP update causes the session to reset
    34Monitor
  • CVE-2024-39552182 days apartJunos OS and Junos OS Evolved: Malformed BGP UPDATE causes RPD crash
    34Monitor
  • CVE-2024-39525272 days apartJunos OS and Junos OS Evolved: When BGP traceoptions is enabled, receipt of specially crafted BGP packet causes RPD crash
    34Monitor
  • CVE-2024-47491274 days apartJunos OS and Junos OS Evolved: Receipt of a specific malformed BGP path attribute leads to an RPD crash
    32Monitor
  • CVE-2023-4418692 days apartJunos OS and Junos OS Evolved: RPD crash when attempting to send a very long AS PATH to a non-4-byte-AS capable BGP neighbor
    30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-755 · Improper Handling of Exceptional Conditions

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records