CVE-2026-57026: Junos OS: MX Series with SPC3, SRX Series: Processing of a specifically malformed SIP invite causes a flowd crash
An Improper Validation of Syntactic Correctness of Input vulnerability in the SIP plugin of Juniper Networks Junos OS on MX Series with SPC3 and SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).If the SIP ALG is enabled on an affected device, the processing of a malformed SIP invite packet will cause a flow processing daemon (flowd) crash and restart. This leads to a complete service outage until the system has automatically recovered.
This issue affects Junos OS on MX Series with SPC3 and SRX Series:
all versions before 23.2R2-S7, 23.4 versions before 23.4R2-S8, 24.2 versions before 24.2R2-S5, 24.4 versions before 24.4R2-S4, 25.2 versions before 25.2R2, 25.4 versions before 25.4R1-S2.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 23.2R2-S7 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 23.4R2-S8 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 24.2R2-S5 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 24.4R2-S4 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 25.2R2 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 25.4R1-S2 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 25.4R2 - Upgrade
Upgrade
Juniper Networks Junos OS (SIP plugin on MX Series with SPC3 and SRX Series)to a version that resolves this vulnerability.Fixed in 26.2R1 - Compensating control
If the SIP ALG is enabled on an affected MX/SPC3 or SRX device, consider disabling SIP ALG to prevent flowd from crashing when processing malformed SIP invite packets.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-57026?
CVE-2026-57026 has a severity rating of high, with a score of 8.7.
How do I fix CVE-2026-57026?
To fix CVE-2026-57026, ensure that the SIP Application Level Gateway (ALG) is disabled on affected Junos OS devices.
What type of attack does CVE-2026-57026 allow?
CVE-2026-57026 allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS) on affected devices.
Which devices are affected by CVE-2026-57026?
CVE-2026-57026 affects Juniper Networks Junos OS on MX Series with SPC3 and SRX Series.
What is the impact of exploiting CVE-2026-57026?
Exploiting CVE-2026-57026 can lead to a crash of the flowd process, resulting in denial of service for legitimate users.