Junos OS (SRX firewalls)
CVE-2024-39555: Receipt of a specific malformed BGP update causes the session to reset
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).
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Junos OS 0 | 21.4R3-S8 or later |
| Junos OS 22.2 | 22.2R3-S4 or later |
| Junos OS 22.3 | 22.3R3-S3 or later |
| Junos OS 22.4 | 22.4R3-S3 or later |
| Junos OS 23.2 | 23.2R2-S1 or later |
| Junos OS 23.4 | 23.4R1-S2, 23.4R2 or later |
| Junos OS Evolved 0 | 21.4R3-S8-EVO or later |
| Junos OS Evolved 22.2-EVO | 22.2R3-S4-EVO or later |
| Junos OS Evolved 22.3-EVO | 22.3R3-S3-EVO or later |
| Junos OS Evolved 22.4-EVO | 22.4R3-S3-EVO or later |
| Junos OS Evolved 23.2-EVO | 23.2R2-S1-EVO or later |
| Junos OS Evolved 23.4-EVO | 23.4R1-S2-EVO, 23.4R2-EVO or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
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.
Am I affected?
A sample BGP segment routing configuration is shown below:
[ protocols bgp group <name> family inet segment-routing-te ] (IPv4)
[ protocols bgp group <name> family inet6 segment-routing-te ] (IPv6)
Workarounds
There are no known workarounds for this issue.
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.