JunosOperating system · Juniper

CVE-2023-22408

HIGH · 7.5 CVSS v3.1 Published 2023-01-13

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

An Improper Validation of Array Index vulnerability in the SIP ALG of Juniper Networks Junos OS on SRX 5000 Series allows a network-based, unauthenticated attacker to cause a Denial of Service (DoS). When an attacker sends an SIP packets with a malformed SDP field then the SIP ALG can not process it which will lead to an FPC crash and restart. Continued receipt of these specific packets will lead to a sustained Denial of Service. This issue can only occur when both below mentioned conditions are fulfilled: 1. Call distribution needs to be enabled: [security alg sip enable-call-distribution] 2. The SIP ALG needs to be enabled, either implicitly / by default or by way of configuration. To confirm whether SIP ALG is enabled on SRX, and MX with SPC3 use the following command: user@host> show security alg status | match sip SIP : Enabled This issue affects Juniper Networks Junos OS on SRX 5000 Series: 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-S2; 22.1 versions prior to 22.1R2-S2, 22.1R3; 22.2 versions prior to 22.2R3; 22.3 versions prior to 22.3R1-S1, 22.3R2. This issue does not affect Juniper Networks Junos OS versions prior to 20.4R1.

Technical summary

dbcve analysis · high confidence

Improper validation of array index in the SIP ALG on Juniper SRX 5000 Series allows unauthenticated network attackers to crash the FPC by sending malformed SIP packets with invalid SDP fields. The vulnerability requires both SIP ALG enabled and call distribution enabled to be exploitable.

MitigationDisable SIP ALG call distribution and SIP ALG if not required, or upgrade to fixed Junos versions (20.4R3-S5, 21.1R3-S4, 21.2R3-S3, 21.3R3-S3, 21.4R3-S2, 22.1R2-S2/22.1R3, 22.2R3, 22.3R1-S1/22.3R2 or later).

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

Affected products & versions

NVD · CPE data

JunosOperating system

Affected:= 20.4= 21.1= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3

CVSS breakdown

From the vector

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

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

Am I affected?

dbcve checks

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

Identify Junos version

Run 'show version' or 'show system information' on the SRX device and note the installed Junos version

Affected if The installed version matches 20.4, 21.1, 21.2, 21.3, 21.4, 22.1, 22.2, or 22.3 (the vulnerable release families)
Verify SIP ALG is enabled

Run 'show security alg sip' and check the output for ALG status, or view the configuration with 'show configuration security alg sip'

Affected if The SIP ALG status shows as enabled or the configuration contains 'alg sip enable'
Confirm call distribution is enabled

Run 'show security alg sip call-distribution' or check the SIP ALG configuration for call-distribution settings

Affected if Call distribution is shown as enabled or the configuration contains 'call-distribution' under the SIP ALG settings
Determine exploitability

If the Junos version is in the affected list AND both SIP ALG and call distribution are enabled, the device is vulnerable

Affected if All three conditions are true: vulnerable Junos version, SIP ALG enabled, and call distribution enabled

The device is affected only if it runs a vulnerable Junos version (20.4, 21.1-21.4, 22.1-22.3) AND has both SIP ALG and call distribution enabled simultaneously.

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

Remediation

dbcve · scoped

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Disable SIP ALG call distribution and SIP ALG if not required, or upgrade to fixed Junos versions (20.4R3-S5, 21.1R3-S4, 21.2R3-S3, 21.3R3-S3, 21.4R3-S2, 22.1R2-S2/22.1R3, 22.2R3, 22.3R1-S1/22.3R2 or later).

Recommended fix High confidence

22.3R2 or later (or any of: 20.4R3-S5, 21.1R3-S4, 21.2R3-S3, 21.3R3-S3, 21.4R3-S2, 22.1R3, 22.2R3, 22.3R1-S1, 22.3R2)

1. Identify the current Junos OS version on the SRX 5000 Series device using: `show version`
2. Plan maintenance window as upgrade will require device restart
3. Download the appropriate fixed Junos OS image (22.3R2 or later recommended) from the Juniper Networks download portal
4. Upload the new Junos OS image to the device: `file copy <source> /var/tmp/`
5. Install the new Junos OS package: `request system software add /var/tmp/<image-name>`
6. Reboot the device to complete installation: `request system reboot`
7. After reboot, verify the new version is running: `show version`
8. Verify SIP ALG status: `show security alg status | match sip`

Caveat Standard Junos upgrade risks apply - review release notes for any configuration syntax changes between your current version and target version

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

Fix this in Junos Scoped from the published advisory

Consultation2.0 h
Implementation4.0 h
Testing3.0 h
Review / QA1.0 h

10.0 hours of engineering $1,750

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References

Primary sources

kb.juniper.netVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-22408 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2023-22408?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 0.6%

Affects: Junos

Remediation

A high-priority fix

Fix this in Junos 10 hrs · Moderate

Typical engagement from $1,750

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2023-22408 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References