CVE-2026-57026 Junos OS: MX Series with SPC3, SRX Series: Processing of a specifically malformed SIP invite causes a flowd crash
An unauthenticated attacker can cause a flowd crash and service outage on Juniper MX and SRX devices by sending a malformed SIP invite if SIP ALG is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-57026?
CVE-2026-57026 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-1286
Which versions are affected by CVE-2026-57026?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2026-57026?
No fix has been published for CVE-2026-57026 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-57026 being exploited?
There is no known exploitation of CVE-2026-57026 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-q2w6-r35r-2hxj.