CVE-2026-33790

Published Apr 9, 2026

Last updated 3 months ago

Overview

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.
Source
sirt@juniper.net
NVD status
Analyzed
Products
junos

Risk scores

CVSS 4.0

Type
Secondary
Base score
8.7
Impact score
-
Exploitability score
-
Vector string
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
Severity
HIGH

CVSS 3.1

Type
Primary
Base score
7.5
Impact score
3.6
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity
HIGH

Weaknesses

sirt@juniper.net
CWE-754

Social media

Hype score
Not currently trending

Configurations

  1. A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). As part of the stateful traffic processing on SRX Series devices flows are being established, and removed when not needed anymore. During the removal process the timeout of a flow should be set to 3 seconds and consequentially the flow should be removed shortly after. Due to a race condition occurring when setting the timeout there is a chance (the exact conditions are outside the attackers control) that the timeout is instead set to a very high value of larger than 10,000 seconds: user@host> show security flow session | match timeout Session ID: 98784248524, Policy name: PROD-FLOW/4, HA State: Active, Timeout: 85250, Session State: Valid This will lead to an accumulation of flows which can be observed by an ever-increasing value of invalidated sessions in the output of 'show security flow session summary': user@host> show security flow session summary | match invalid Invalidated sessions: 216931These sessions can't be cleared manually with the 'clear security flow session' command, which will either lead to forwarding to stop (and the system needs to be manually recovered with a reboot) or to a flowd core and automatic reboot. This issue affects Junos OS on SRX Series: * 24.2 versions before 24.2R2-S3, * 24.4 versions before 24.4R2-S1, 24.4R2-S2, * 25.2 versions before 25.2R1-S2, 25.2R2. This issue does not affect releases earlier than 24.2R1;CVE-2026-57030

References

Sources include official advisories and independent security research.