Juniper Junos OS up to 25.4R1-S1 SIP ALG input validation

Summaryinfo

A vulnerability marked as critical has been reported in Juniper Junos OS up to 25.4R1-S1. The affected element is an unknown function of the component SIP ALG. The manipulation leads to input validation. This vulnerability is traded as CVE-2026-57026. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Juniper Junos OS up to 25.4R1-S1 and classified as critical. This issue affects an unknown code of the component SIP ALG. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is availability. The summary by CVE is:

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.

It is possible to read the advisory at supportportal.juniper.net. The identification of this vulnerability is CVE-2026-57026 since 06/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/10/2026).

Upgrading to version 23.2R2-S7, 23.4R2-S8, 24.2R2-S5, 24.4R2-S4, 25.2R2 or 25.4R1-S2 eliminates this vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Juniper

Name

• Junos OS

Version

• 23.2R2-S6
• 23.4R2-S7
• 24.2R2-S4
• 24.4R2-S3
• 25.2R1
• 25.4R1-S1

License

• commercial

Website

• Vendor: https://www.juniper.net/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion