CVE-2026-33790: CWE-754 Improper Check for Unusual or Exceptional Conditions in Juniper Networks Junos OS
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.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-33790) in Juniper Networks Junos OS SRX Series arises from an improper check for unusual or exceptional conditions (CWE-754) in the flow daemon (flowd). When the device processes a specific malformed ICMPv6 packet during NAT64 translation, the srxpfe process crashes and restarts, causing a Denial of Service (DoS) condition. The issue is limited to ICMPv6 packets and cannot be triggered by IPv4 or other IPv6 traffic. Affected versions span multiple releases before certain patch levels from 21.2R3-S10 through 25.2R2. The vulnerability has a CVSS 3.1 base score of 7.5, indicating high severity with network attack vector, low attack complexity, no privileges or user interaction required, and impact limited to availability. The vendor manages remediation for this cloud-hosted service, and a patch is available.
Potential Impact
Successful exploitation causes the srxpfe process on affected Junos OS SRX Series devices to crash and restart repeatedly, resulting in a sustained Denial of Service (DoS) condition. This disrupts normal device operation and availability. The vulnerability does not impact confidentiality or integrity, only availability. It cannot be triggered by IPv4 or other IPv6 traffic, only by specific malformed ICMPv6 packets during NAT64 translation.
Mitigation Recommendations
A patch is available for this vulnerability. Since Junos OS on SRX Series is a cloud-managed service, the vendor typically applies remediation server-side. Users should verify with Juniper Networks advisories to confirm patch deployment status and apply any recommended updates promptly to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-33790: CWE-754 Improper Check for Unusual or Exceptional Conditions in Juniper Networks Junos OS
Description
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-33790) in Juniper Networks Junos OS SRX Series arises from an improper check for unusual or exceptional conditions (CWE-754) in the flow daemon (flowd). When the device processes a specific malformed ICMPv6 packet during NAT64 translation, the srxpfe process crashes and restarts, causing a Denial of Service (DoS) condition. The issue is limited to ICMPv6 packets and cannot be triggered by IPv4 or other IPv6 traffic. Affected versions span multiple releases before certain patch levels from 21.2R3-S10 through 25.2R2. The vulnerability has a CVSS 3.1 base score of 7.5, indicating high severity with network attack vector, low attack complexity, no privileges or user interaction required, and impact limited to availability. The vendor manages remediation for this cloud-hosted service, and a patch is available.
Potential Impact
Successful exploitation causes the srxpfe process on affected Junos OS SRX Series devices to crash and restart repeatedly, resulting in a sustained Denial of Service (DoS) condition. This disrupts normal device operation and availability. The vulnerability does not impact confidentiality or integrity, only availability. It cannot be triggered by IPv4 or other IPv6 traffic, only by specific malformed ICMPv6 packets during NAT64 translation.
Mitigation Recommendations
A patch is available for this vulnerability. Since Junos OS on SRX Series is a cloud-managed service, the vendor typically applies remediation server-side. Users should verify with Juniper Networks advisories to confirm patch deployment status and apply any recommended updates promptly to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- juniper
- Date Reserved
- 2026-03-23T19:46:13.672Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Is Cloud Service
- true
Threat ID: 69d822bf1cc7ad14da2ad16a
Added to database: 4/9/2026, 10:05:51 PM
Last enriched: 4/9/2026, 10:21:06 PM
Last updated: 4/10/2026, 8:13:37 AM
Views: 10
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