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Fencer Vulns
high 7.5

CVE-2024-39555 json

Junos OS and Junos OS Evolved: Receipt of a specific malformed BGP update causes the session to reset

published 2024-07-10 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-38081

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

An Improper Handling of Exceptional Conditions vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an attacker sending a specific malformed BGP update message to cause the session to reset, resulting in a Denial of Service (DoS). Continued receipt and processing of these malformed BGP update messages will create a sustained Denial of Service (DoS) condition.

Upon receipt of a BGP update message over an established BGP session containing a specifically malformed tunnel encapsulation attribute, when segment routing is enabled, internal processing of the malformed attributes within the update results in improper parsing of remaining attributes, leading to session reset:

BGP SEND Notification code 3 (Update Message Error) subcode 1 (invalid attribute list)

Only systems with segment routing enabled are vulnerable to this issue.

This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations, and requires a remote attacker to have at least one established BGP session.

This issue affects:

Junos OS:

* All versions before 21.4R3-S8, * from 22.2 before 22.2R3-S4, * from 22.3 before 22.3R3-S3, * from 22.4 before 22.4R3-S3, * from 23.2 before 23.2R2-S1, * from 23.4 before 23.4R1-S2, 23.4R2.

Junos OS Evolved:

* All versions before 21.4R3-S8-EVO, * from 22.2-EVO before 22.2R3-S4-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R3-S3-EVO, * from 23.2-EVO before 23.2R2-S1-EVO, * from 23.4-EVO before 23.4R1-S2-EVO, 23.4R2-EVO.

Patch / fix

  • Juniper Networks Junos OS 21.4R3-S8, 22.2R3-S4, 22.3R3-S3, 22.4R3-S3, 23.2R2-S1, 23.4R1-S2, 23.4R2
  • Juniper Networks Junos OS Evolved 21.4R3-S8-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S3-EVO, 23.2R2-S1-EVO, 23.4R1-S2-EVO, 23.4R2-EVO
  • juniper junos_os 21.4R3-S8, 22.2R3-S4, 22.3R3-S3, 22.4R3-S3, 23.2R2-S1, 23.4R1-S2, 23.4R2
  • juniper junos_os_evolved 21.4R3-S8-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S3-EVO, 23.2R2-S1-EVO, 23.4R1-S2-EVO, 23.4R2-EVO

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/R:A
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:A/V:X/RE:X/U:X

Affected products

  • Juniper Networks Junos OS
  • Juniper Networks Junos OS Evolved
  • juniper junos_os
  • juniper junos_os_evolved

Classification

Weakness
  • CWE-755 Improper Handling of Exceptional Conditions

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.