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Juniper EUVDEUVD-2026-21206

| CVE-2026-33790 HIGH
Improper Check for Unusual or Exceptional Conditions (CWE-754)
2026-04-09 sirt@juniper.net GHSA-9cqr-g7fq-8jf6
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:A/V:C/RE:M/U:Amber

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

Lifecycle Timeline

7
Re-analysis Queued
Apr 17, 2026 - 17:22 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
25.2R1-S2,21.2R3-S10,21.4R3-S12
EUVD ID Assigned
Apr 09, 2026 - 22:22 euvd
EUVD-2026-21206
Analysis Generated
Apr 09, 2026 - 22:22 vuln.today
CVE Published
Apr 09, 2026 - 22:16 nvd
HIGH 8.7

DescriptionCVE.org

An Improper Check for Unusual or Exceptional Conditions vulnerability in the flow daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an attacker sending a specific, malformed ICMPv6 packet to cause the srxpfe process to crash and restart. Continued receipt and processing of these packets will repeatedly crash the srxpfe process and sustain the Denial of Service (DoS) condition.

During NAT64 translation, receipt of a specific, malformed ICMPv6 packet destined to the device will cause the srxpfe process to crash and restart.

This issue cannot be triggered using IPv4 nor other IPv6 traffic.

This issue affects Junos OS on SRX Series:

  • all versions before 21.2R3-S10,
  • all versions of 21.3,
  • from 21.4 before 21.4R3-S12,
  • all versions of 22.1,
  • from 22.2 before 22.2R3-S8,
  • all versions of 22.4,
  • from 22.4 before 22.4R3-S9,
  • from 23.2 before 23.2R2-S6,
  • from 23.4 before 23.4R2-S7,
  • from 24.2 before 24.2R2-S3,
  • from 24.4 before 24.4R2-S3,
  • from 25.2 before 25.2R1-S2, 25.2R2.

AnalysisAI

Denial of service in Juniper Networks Junos OS on SRX Series allows unauthenticated remote attackers to crash srxpfe process via malformed ICMPv6 packets during NAT64 translation. Repeated exploitation sustains DoS by forcing continuous process restarts. Affects wide range of Junos OS versions from 21.2 through 25.2 on SRX hardware. Vulnerability limited to ICMPv6 traffic; IPv4 and standard IPv6 cannot trigger. No public exploit identified at time of analysis.

Technical ContextAI

Improper exception handling (CWE-754) in flow daemon (flowd) fails to validate ICMPv6 packet structure during NAT64 address translation operations. Malformed ICMPv6 packets destined to device trigger unhandled exception in srxpfe process, causing immediate crash. IPv4 and non-malformed IPv6 traffic unaffected due to different processing paths bypassing vulnerable validation logic.

RemediationAI

Vendor-released patches: upgrade to Junos OS 21.2R3-S10, 21.4R3-S12, 22.2R3-S8, 22.4R3-S9, 23.2R2-S6, 23.4R2-S7, 24.2R2-S3, 24.4R2-S3, 25.2R1-S2, or 25.2R2 depending on deployment branch. Workarounds for environments unable to immediately patch: disable NAT64 translation if not operationally required; implement ingress filtering to block malformed ICMPv6 packets at network perimeter; apply strict ICMPv6 type/code filtering on untrusted interfaces. Full vendor advisory and patch details: https://kb.juniper.net/JSA107874

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EUVD-2026-21206 vulnerability details – vuln.today
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