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Juniper EUVDEUVD-2026-21197

| CVE-2026-33778 HIGH
Improper Validation of Syntactic Correctness of Input (CWE-1286)
2026-04-09 sirt@juniper.net GHSA-q559-6pc6-gxfh
Juniper Denial Of Service
8.7
CVSS 4.0 · NVD
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Severity by source

NVD 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:X/V:X/RE:M/U:X

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

Lifecycle Timeline

7
Re-analysis Queued
Apr 17, 2026 - 17:37 vuln.today
cvss_changed
Analysis Updated
Apr 16, 2026 - 05:59 EUVD-patch-fix
executive_summary
Re-analysis Queued
Apr 16, 2026 - 05:29 backfill_euvd_patch
patch_released
Patch available
Apr 16, 2026 - 05:29 EUVD
24.2R2-S4,23.2R2-S6,22.4R3-S9
EUVD ID Assigned
Apr 09, 2026 - 22:22 euvd
EUVD-2026-21197
Analysis Generated
Apr 09, 2026 - 22:22 vuln.today
CVE Published
Apr 09, 2026 - 22:16 nvd
HIGH 8.7

DescriptionCVE.org

An Improper Validation of Syntactic Correctness of Input vulnerability in the IPsec library used by kmd and iked of Juniper Networks Junos OS on SRX Series and MX Series allows an unauthenticated, network-based attacker to cause a complete Denial-of-Service (DoS).

If an affected device receives a specifically malformed first ISAKMP packet from the initiator, the kmd/iked process will crash and restart, which momentarily prevents new security associations (SAs) for from being established. Repeated exploitation of this vulnerability causes a complete inability to establish new VPN connections.

This issue affects Junos OS on

SRX Series and MX Series:

  • all versions before 22.4R3-S9,
  • 23.2 version before 23.2R2-S6,
  • 23.4 version before 23.4R2-S7,
  • 24.2 versions before 24.2R2-S4,
  • 24.4 versions before 24.4R2-S3,
  • 25.2 versions before 25.2R1-S2, 25.2R2.

AnalysisAI

Remote denial-of-service in Juniper Networks Junos OS (SRX/MX Series) allows unauthenticated attackers to crash IPsec daemons via malformed ISAKMP packets. Exploiting the improper input validation (CWE-1286) in kmd/iked IPsec library causes process restart, preventing new VPN security association establishment. Repeated attacks create sustained inability to establish VPN connections, severely degrading network connectivity for affected enterprise firewalls and routing platforms. No public exploit identified at time of analysis.

Technical ContextAI

Root cause: IPsec library fails to validate syntactic correctness of first ISAKMP packet from initiator (CWE-1286). Malformed packet triggers kmd/iked process crash in Junos OS IPsec implementation on SRX Series (cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*) and MX Series platforms. Attack vector network-based, requires no authentication (CVSS PR:N), low complexity (AC:L).

RemediationAI

Vendor-released patches available: upgrade to Junos OS 22.4R3-S9, 23.2R2-S6, 23.4R2-S7, 24.2R2-S4, 24.4R2-S3, 25.2R1-S2, or 25.2R2 depending on deployed release track. Prioritize patching internet-facing SRX/MX devices with active IPsec/VPN configurations. No workaround provided; mitigation requires applying vendor patches. Implement network-layer access controls to restrict ISAKMP (UDP 500/4500) traffic to trusted IPsec peers as temporary risk reduction. Review Juniper security bulletin for deployment guidance: https://kb.juniper.net/JSA107868. Validate IPsec functionality post-upgrade and monitor kmd/iked process stability.

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EUVD-2026-21197 vulnerability details – vuln.today
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