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JunosOperating system · Juniper

CVE-2022-22167

CRITICAL · 9.8 CVSS v3.1 Published 2022-01-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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. While JDPI correctly classifies out-of-state asymmetric TCP flows as the dynamic-application UNKNOWN, this classification is not provided to the policy module properly and hence traffic continues to use the pre-id-default-policy, 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-S10, 18.4R3-S10; 19.1 versions prior to 19.1R3-S8; 19.2 versions prior to 19.2R1-S8, 19.2R3-S4; 19.3 versions prior to 19.3R3-S3; 19.4 versions prior to 19.4R3-S5; 20.1 versions prior to 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R2-S2, 20.4R3; 21.1 versions prior to 21.1R2-S2, 21.1R3; 21.2 versions prior to 21.2R2. This issue does not affect Juniper Networks Junos OS versions prior to 18.4R1.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A traffic classification vulnerability in Juniper Junos OS on SRX Series allows attackers to bypass Juniper Deep Packet Inspection (JDPI) rules when 'no-syn-check' is configured. While JDPI correctly classifies out-of-state asymmetric TCP flows as UNKNOWN, this classification isn't properly passed to the policy module, causing traffic to use the more permissive pre-id-default-policy instead of the intended restrictive policy, allowing unauthorized traffic to be forwarded.

MitigationUpgrade Junos OS to a fixed version (18.4R2-S10 or later, 19.1R3-S8 or later, etc.) or disable 'set security flow tcp-session no-syn-check' if the functionality is not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:= 18.4= 19.1= 19.2= 19.3= 19.4= 20.1= 20.2= 20.3= 20.4= 21.1= 21.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm device is SRX Series
    Run 'show chassis hardware' or 'show system information' to verify the device model is from the SRX product line
    Affected if Device is not an SRX Series - the vulnerability only affects SRX Series devices
  2. Check Junos OS version
    Run 'show version' and compare the installed version against the affected list: 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3, 20.4, 21.1, 21.2
    Affected if Installed version matches one of the affected versions listed in the CVE
  3. Verify no-syn-check is enabled
    Run 'show configuration security flow tcp-session' and look for the 'no-syn-check' setting, or search config with 'show configuration | match no-syn-check'
    Affected if 'no-syn-check' is configured - this is the required condition for the vulnerability to be exploitable
  4. Identify security policies using application services
    Run 'show configuration security policies' and review policies for 'application' or 'jdpi' related configurations that rely on Deep Packet Inspection
    Affected if Security policies exist that depend on JDPI classification for out-of-state TCP traffic
  5. Check for asymmetric traffic patterns
    Monitor traffic logs or run 'show security flow session' to identify TCP sessions that are established without proper SYN validation (out-of-state flows)
    Affected if Asymmetric TCP traffic flows exist that would be classified as UNKNOWN by JDPI

Device is affected if it is an SRX Series running a vulnerable Junos version (18.4-21.2) with 'no-syn-check' configured AND has security policies that rely on JDPI application classification for TCP traffic.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Junos OS to a fixed version (18.4R2-S10 or later, 19.1R3-S8 or later, etc.) or disable 'set security flow tcp-session no-syn-check' if the functionality is not required.

Recommended fix High confidence

18.4R2-S10, 18.4R3-S10, 19.1R3-S8, 19.2R1-S8, 19.2R3-S4, 19.3R3-S3 or later (depending on current branch)

  1. Identify the current Junos OS version on the SRX Series device using: show version
  2. Check if the vulnerable 'no-syn-check' option is configured: show configuration security flow tcp-session
  3. Upgrade Junos OS to a fixed version based on the current branch: For 18.4x - upgrade to 18.4R2-S10 or 18.4R3-S10; For 19.1x - upgrade to 19.1R3-S8; For 19.2x - upgrade to 19.2R1-S8 or 19.2R3-S4; For 19.3x - upgrade to 19.3R3-S3; For newer branches - upgrade to the latest available patched release
  4. After upgrade, verify the configuration: show configuration security flow tcp-session
  5. Verify that security policies are correctly enforcing JDPI classifications for asymmetric TCP flows
  6. Test that traffic classification is working properly and policies are being applied correctly
Caveat Ensure to review release notes for any compatibility concerns before upgrading; always test in a non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,120
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-22167 in production — separate from our analysis above.

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What this is

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What belongs here
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