CVE-2024-21587

Summary

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.

Affected Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OS0 < 20.4R3-S9affected
Juniper NetworksJunos OS21.2 < 21.2R3-S7affected
Juniper NetworksJunos OS21.3 < 21.3R3-S5affected
Juniper NetworksJunos OS21.4 < 21.4R3-S5affected
Juniper NetworksJunos OS22.1 < 22.1R3-S4affected
Juniper NetworksJunos OS22.2 < 22.2R3-S3affected
Juniper NetworksJunos OS22.3 < 22.3R3-S2affected
Juniper NetworksJunos OS22.4 < 22.4R2-S2, 22.4R3affected
Juniper NetworksJunos OS23.2 < 23.2R1-S1, 23.2R2affected

Weaknesses

  • CWE-755: CWE-755 Improper Handling of Exceptional Conditions
  • Denial of Service (DoS)

Workarounds

This issue can be mitigated by disabling BFD liveness detection for DHCP subscribers.

Service can be restored by manually restarting the bbe-smgd process periodically.

ADP Enrichment

CVE Program Container

Additional References

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References