title: Junos OS: SRX Series: Denial of service vulnerability in flowd daemon upon receipt of a specific fragmented packet
description: A vulnerability in Juniper Networks Junos OS on SRX Series, allows a network-based unauthenticated attacker to cause a Denial of Service (DoS) by sending a specific fragmented packet to the device, resulting in a flowd process crash, which is responsible for packet forwarding. Continued receipt and processing of this specific packet will create a sustained DoS condition. This issue only affects SRX Series when 'preserve-incoming-fragment-size' feature is enabled. This issue affects Juniper Networks Junos OS on SRX Series: 18.3 versions prior to 18.3R3-S6; 18.4 versions prior to 18.4R3-S10; 19.1 versions prior to 19.1R3-S7; 19.2 versions prior to 19.2R3-S4; 19.3 versions prior to 19.3R3-S4; 19.4 versions prior to 19.4R3-S6; 20.1 versions prior to 20.1R3-S2; 20.2 versions prior to 20.2R3-S3; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2-S1, 21.1R3; 21.2 versions prior to 21.2R2. This issue does not affect Juniper Networks Junos OS prior to 17.3R1.
problem types: CWE-754 Improper Check for Unusual or Exceptional Conditions
affected:
{
platforms: SRX Series
product: Junos OS
vendor: Juniper Networks
versions:
lessThan: 18.3R3-S6, status: affected, version: unspecified, versionType: custom
lessThan: 17.3R1, status: unaffected, version: unspecified, versionType: custom
lessThan: 17.3*, status: affected, version: 17.3R1, versionType: custom
lessThan: 18.4R3-S10, status: affected, version: 18.4, versionType: custom
lessThan: 19.1R3-S7, status: affected, version: 19.1, versionType: custom
lessThan: 19.2R3-S4, status: affected, version: 19.2, versionType: custom
lessThan: 19.3R3-S4, status: affected, version: 19.3, versionType: custom
lessThan: 19.4R3-S6, status: affected, version: 19.4, versionType: custom
lessThan: 20.1R3-S2, status: affected, version: 20.1, versionType: custom
lessThan: 20.2R3-S3, status: affected, version: 20.2, versionType: custom
lessThan: 20.3R3-S1, status: affected, version: 20.3, versionType: custom
lessThan: 20.4R3, status: affected, version: 20.4, versionType: custom
lessThan: 21.1R2-S1, 21.1R3, status: affected, version: 21.1, versionType: custom
lessThan: 21.2R2, status: affected, version: 21.2, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 7.5
baseSeverity: HIGH
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
version: 3.1
]
exploits: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
solutions: The following software releases have been updated to resolve this specific issue: 18.3R3-S6, 18.4R3-S10, 19.1R3-S7, 19.2R3-S4, 19.3R3-S4, 19.4R3-S6, 20.1R3-S2, 20.2R3-S3, 20.3R3-S1, 20.4R3, 21.1R2-S1, 21.1R3, 21.2R2, 21.3R1, and all subsequent releases.
workarounds: An administrator can disable the feature preserve-incoming-fragment-size to avoid this issue:
user@host# delete security flow preserve-incoming-fragment-size
user@host# commit