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CVE-2022-22157

Junos OS: SRX Series: Traffic classification vulnerability when 'no-syn-check' is enabled

High7.2EPSS 0.66%
Published
Updated
Reserved
Assigned by
juniper

Description

A traffic classification vulnerability in Juniper Networks Junos OS on the SRX Series Services Gateways may allow an attacker to bypass Juniper Deep Packet Inspection (JDPI) rules and access unauthorized networks or resources, when 'no-syn-check' is enabled on the device. JDPI incorrectly classifies out-of-state asymmetric TCP flows as the dynamic-application INCONCLUSIVE instead of UNKNOWN, which is more permissive, causing the firewall to allow traffic to be forwarded that should have been denied. This issue only occurs when 'set security flow tcp-session no-syn-check' is configured on the device. This issue affects Juniper Networks Junos OS on SRX Series: 18.4 versions prior to 18.4R2-S9, 18.4R3-S9; 19.1 versions prior to 19.1R2-S3, 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S2; 19.4 versions prior to 19.4R2-S5, 19.4R3-S3; 20.1 versions prior to 20.1R2-S2, 20.1R3; 20.2 versions prior to 20.2R3-S1; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2. This issue does not affect Juniper Networks Junos OS versions prior to 18.4R1.

Scores

CVSS scores of CVE-2022-22157, by who scored it
Scored byCVSSScoreVector
juniperCNA (assigner)3.1High7.2CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
NVDNVD · Modified3.1Critical9.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
EPSS (exploitation in 30 days)
0.66% · top 48% of all CVEs (6 Nov 2026)
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.2.

Weakness

Affected products

  • Juniper Networks · Junos OS

    • affected 18.4 – < 18.4R2-S9, 18.4R3-S9
    • affected 19.1 – < 19.1R2-S3, 19.1R3-S6
    • affected 19.2 – < 19.2R1-S7, 19.2R3-S3
    • affected 19.3 – < 19.3R2-S6, 19.3R3-S2
    • affected 19.4 – < 19.4R2-S5, 19.4R3-S3
    • affected 20.1 – < 20.1R2-S2, 20.1R3
    • affected 20.2 – < 20.2R3-S1
    • affected 20.3 – < 20.3R3
    • affected 20.4 – < 20.4R2-S1, 20.4R3
    • affected 21.1 – < 21.1R1-S1, 21.1R2

  • Juniper Networks · Junos OS

    • unaffected unspecified – < 18.4R1

What to do

Solution: The following software releases have been updated to resolve this specific issue: Junos OS 18.4R2-S9, 18.4R3-S9, 19.1R2-S3, 19.1R3-S6, 19.2R1-S7, 19.2R3-S3, 19.3R2-S6, 19.3R3-S2, 19.4R2-S5, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R3-S1, 20.3R3, 20.4R2-S1, 20.4R3, 21.1R1-S1, 21.1R2, 21.2R1, and all subsequent releases.

Workaround: Any of the following workarounds will mitigate this issue: 1. Remove 'security flow tcp-session no-syn-check' from the configuration. 2: Enable AppID cache configuration: set services application-identification application-system-cache security-services

Exploitation: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .