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JunosOperating system · Juniper

CVE-2023-22409

MEDIUM · 5.5 CVSS v3.1 Published 2023-01-13
Fix available
A fix is available. Upgrade to 19.4 or later.
See remediation →
57/100
Remediation priority · Elevated
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
An Unchecked Input for Loop Condition vulnerability in a NAT library of Juniper Networks Junos OS allows a local authenticated attacker with low privileges to cause a Denial of Service (DoS). When an inconsistent "deterministic NAT" configuration is present on an SRX, or MX with SPC3 and then a specific CLI command is issued the SPC will crash and restart. Repeated execution of this command will lead to a sustained DoS. Such a configuration is characterized by the total number of port blocks being greater than the total number of hosts. An example for such configuration is: [ services nat source pool TEST-POOL address x.x.x.0/32 to x.x.x.15/32 ] [ services nat source pool TEST-POOL port deterministic block-size 1008 ] [ services nat source pool TEST-POOL port deterministic host address y.y.y.0/24] [ services nat source pool TEST-POOL port deterministic include-boundary-addresses] where according to the following calculation: 65536-1024=64512 (number of usable ports per IP address, implicit) 64512/1008=64 (number of port blocks per Nat IP) x.x.x.0/32 to x.x.x.15/32 = 16 (NAT IP addresses available in NAT pool) total port blocks in NAT Pool = 64 blocks per IP * 16 IPs = 1024 Port blocks host address y.y.y.0/24 = 256 hosts (with include-boundary-addresses) If the port block size is configured to be 4032, then the total port blocks are (64512/4032) * 16 = 256 which is equivalent to the total host addresses of 256, and the issue will not be seen. This issue affects Juniper Networks Junos OS on SRX Series, and MX Series with SPC3: All versions prior to 19.4R3-S10; 20.1 version 20.1R1 and later versions; 20.2 versions prior to 20.2R3-S6; 20.3 versions prior to 20.3R3-S6; 20.4 versions prior to 20.4R3-S5; 21.1 versions prior to 21.1R3-S4; 21.2 versions prior to 21.2R3-S3; 21.3 versions prior to 21.3R3-S3; 21.4 versions prior to 21.4R3-S1; 22.1 versions prior to 22.1R2-S2, 22.1R3; 22.2 versions prior to 22.2R2.

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 local authenticated attacker with low privileges can cause denial of service on SRX Series or MX Series with SPC3 by issuing a specific CLI command when a deterministic NAT configuration has more port blocks than hosts (e.g., block-size 1008 with 16 NAT IPs and 256 hosts results in 1024 port blocks exceeding 256 hosts). The vulnerability stems from an unchecked loop condition in the NAT library that causes the SPC to crash and restart.

MitigationApply Juniper software patches for affected versions (21.1R3-S4, 21.2R3-S3, 21.3R3-S3, 21.4R3-S1, 22.1R2-S2/22.1R3, 22.2R2 and later) or modify NAT configuration to ensure port blocks do not exceed host addresses (e.g., increase block-size to 4032).

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:< 19.4= 19.4= 20.1= 20.2= 20.3= 20.4= 21.1= 21.2= 21.3= 21.4= 22.1= 22.2

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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. Identify device model and hardware
    Run 'show chassis hardware' or check device model. Confirm it is SRX Series or MX Series with SPC3 cards.
    Affected if Device is not SRX or MX Series with SPC3 hardware - vulnerability does not apply.
  2. Check Junos software version
    Run 'show version' to obtain the installed Junos version.
    Affected if Version is one of the affected versions: < 19.4, 19.4, 20.1, 20.2, 20.3, 20.4, 21.1, 21.2, 21.3, 21.4, 22.1, or 22.2.
  3. Verify deterministic NAT is configured
    Run 'show configuration | display set | match deterministic' or review NAT configuration in set format.
    Affected if No deterministic NAT configuration exists - vulnerability cannot be triggered.
  4. Calculate port block to host ratio
    From the deterministic NAT configuration, identify: block-size value, number of NAT IP addresses, and host count. Compute: (block-size x number of NAT IPs). Compare to host count.
    Affected if The product of block-size and NAT IP count exceeds the host count (e.g., block-size 1008 with 16 NAT IPs = 1024 port blocks, but only 256 hosts).

A user is affected if they are running a vulnerable Junos version on SRX/MX with SPC3, have deterministic NAT configured, and the number of port blocks (block-size × NAT IPs) exceeds the number of hosts.

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
Upgrade available Upgrade to 19.4 or later
Fixed in 19.4
Interim mitigation

Apply Juniper software patches for affected versions (21.1R3-S4, 21.2R3-S3, 21.3R3-S3, 21.4R3-S1, 22.1R2-S2/22.1R3, 22.2R2 and later) or modify NAT configuration to ensure port blocks do not exceed host addresses (e.g., increase block-size to 4032).

Recommended fix High confidence

Upgrade to 19.4R3-S10 or later (for 19.4 branch), or 20.2R3-S6 or later (for 20.2 branch), or 20.3R3-S6 or later (for 20.3 branch), or 20.4R3-S5 or later (for 20.4 branch), or 21.1R3-S4 or later (for 21.1 branch), or 21.2R3-S3 or later (for 21.2 branch), or 21.3R3-S3 or later (for 21.3 branch), or 2

  1. 1. Identify the currently running Junos OS version on the affected SRX Series or MX Series with SPC3 device
  2. 2. Review the deterministic NAT configuration on the device to confirm if it matches the vulnerable pattern (port blocks > hosts)
  3. 3. Plan for a maintenance window to perform the upgrade
  4. 4. Download the appropriate fixed Junos OS version from the Juniper Networks support portal
  5. 5. Upload the Junos OS upgrade package to the device
  6. 6. Reboot the device to apply the new Junos OS version
  7. 7. After upgrade, verify the device is functioning correctly and the NAT service is operational
  8. 8. Verify the new Junos OS version matches a fixed release: 19.4R3-S10 or later, 20.2R3-S6 or later, 20.3R3-S6 or later, 20.4R3-S5 or later, 21.1R3-S4 or later, 21.2R3-S3 or later, 21.3R3-S3 or later, 21.4R3-S1 or later, 22.1R2-S2/22.1R3 or later, or 22.2R2 or later
Caveat Standard Junos OS upgrade considerations apply - review release notes for any behavioral changes, ensure configuration compatibility, and plan for potential downtime

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2023-22409 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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  • Version or environment caveats, and links to real fixes
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