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Junos OS EUVDEUVD-2026-42714

| CVE-2026-57026 HIGH
Improper Validation of Syntactic Correctness of Input (CWE-1286)
2026-07-09 juniper GHSA-q2w6-r35r-2hxj
8.7
CVSS 4.0 · Vendor: juniper
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Severity by source

Vendor (juniper) PRIMARY
8.7 HIGH
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:Y/R:A/V:X/RE:M/U:X
vuln.today AI
7.5 HIGH

Unauthenticated network-reachable malformed packet (AV:N/AC:L/PR:N/UI:N) crashes flowd for an availability-only impact (A:H); no confidentiality or integrity effect and no scope change.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Primary rating from Vendor (juniper).

CVSS VectorVendor: juniper

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:Y/R:A/V:X/RE:M/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

6
Patch available
Jul 09, 2026 - 23:02 EUVD
Analysis Updated
Jul 09, 2026 - 22:30 vuln.today
v3 (cvss_changed)
Analysis Updated
Jul 09, 2026 - 22:29 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jul 09, 2026 - 22:22 vuln.today
cvss_changed
CVSS changed
Jul 09, 2026 - 22:22 NVD
7.5 (HIGH) 8.7 (HIGH)
Analysis Generated
Jul 09, 2026 - 22:02 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Denial-of-service in Juniper Networks Junos OS on MX Series (with SPC3) and SRX Series devices allows an unauthenticated, network-based attacker to crash the flow processing daemon (flowd) by sending a malformed SIP INVITE packet when the SIP Application Layer Gateway (ALG) is enabled. The crash forces a flowd restart, producing a complete traffic-forwarding outage until the device auto-recovers, and can be repeated to sustain the outage. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Reach device SIP signaling port
Delivery
Craft malformed SIP INVITE
Exploit
Send to SIP ALG parser
Execution
Trigger flowd validation fault
Persist
flowd crashes and restarts
Impact
Repeat to sustain full service outage

Vulnerability AssessmentAI

Exploitation The SIP ALG must be explicitly enabled on the affected MX (SPC3) or SRX device, and the attacker must be able to deliver a malformed SIP INVITE packet to the device's SIP signaling path over the network. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine availability priority for organizations that run SIP ALG on internet- or SIP-trunk-facing SRX/MX devices, tempered by a specific configuration precondition. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker who can reach the SIP signaling port of an internet-facing SRX firewall with SIP ALG enabled sends a single crafted, malformed SIP INVITE packet. flowd fails to validate the request syntax, crashes, and restarts, dropping all traffic through the device; the attacker scripts the packet on a loop to keep the daemon crashing and maintain a sustained outage. …
Remediation Upgrade to a fixed Junos OS release for your train: 23.2R2-S7, 23.4R2-S8, 24.2R2-S5, 24.4R2-S4, 25.2R2, or 25.4R1-S2 (or later), as documented in Juniper advisory JSA110086 (https://supportportal.juniper.net/JSA110086) - Vendor-released patches confirmed per that advisory. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

24 hours: Inventory all MX Series (with SPC3) and SRX Series devices; disable SIP gateway functionality unless operationally critical. …

Sign in for detailed remediation steps and compensating controls.

Threat intelligence, references, and detailed analysis are available after sign-in.

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EUVD-2026-42714 vulnerability details – vuln.today

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