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JunosOperating system · Juniper

CVE-2023-36831

HIGH · 7.5 CVSS v3.1 Published 2023-07-14
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 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 Improper Check or Handling of Exceptional Conditions vulnerability in the UTM (Unified Threat Management) Web-Filtering feature of Juniper Networks Junos OS on SRX Series causes a jbuf memory leak to occur when accessing certain websites, eventually leading to a Denial of Service (DoS) condition. Service restoration is only possible by rebooting the system. The jbuf memory leak only occurs in SSL Proxy and UTM Web-Filtering configurations. Other products, platforms, and configurations are not affected by this vulnerability. This issue affects Juniper Networks Junos OS on SRX Series: 22.2 versions prior to 22.2R3; 22.3 versions prior to 22.3R2-S1, 22.3R3; 22.4 versions prior to 22.4R1-S2, 22.4R2. This issue does not affect Juniper Networks Junos OS 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 memory leak in the UTM Web-Filtering feature of Juniper Junos OS on SRX Series devices causes jbuf memory exhaustion when certain websites are accessed with SSL Proxy enabled. The leak eventually leads to a denial of service condition that can only be resolved by rebooting the device.

MitigationDisable SSL Proxy and UTM Web-Filtering configurations on affected SRX devices, or upgrade to Junos OS versions 22.2R3, 22.3R2-S1/22.3R3, or 22.4R1-S2/22.4R2 or later as appropriate.

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:= 22.2= 22.3= 22.4

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
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? 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
    Run 'show chassis hardware' or 'show system information' to confirm the device is an SRX Series appliance
    Affected if Device is not an SRX Series device - the vulnerability only affects SRX appliances
  2. Check installed Junos version
    Run 'show version' to retrieve the installed Junos OS version
    Affected if Version is 22.2, 22.3, or 22.4 (any build within these release trains)
  3. Verify UTM Web-Filtering is enabled
    Run 'show configuration | display set | match web-filter' or review the UTM configuration for web-filtering features
    Affected if UTM web-filtering feature is configured and active on the device
  4. Confirm SSL Proxy is active
    Run 'show configuration | display set | match ssl-proxy' or check security policies for ssl-proxy settings
    Affected if SSL Proxy is enabled in the security configuration or policies
  5. Monitor jbuf memory usage
    Run 'show system memory' or 'show system buffers' repeatedly over time to observe jbuf memory consumption patterns
    Affected if jbuf memory shows continuous growth or exhaustion without recovery, indicating the leak is occurring

Device is affected if it is an SRX Series running Junos 22.2/22.3/22.4 with both UTM Web-Filtering and SSL Proxy concurrently enabled, and jbuf memory is exhibiting abnormal growth or exhaustion.

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

Disable SSL Proxy and UTM Web-Filtering configurations on affected SRX devices, or upgrade to Junos OS versions 22.2R3, 22.3R2-S1/22.3R3, or 22.4R1-S2/22.4R2 or later as appropriate.

Recommended fix High confidence

Upgrade to Junos OS 22.2R3 or later for the 22.2 branch; 22.3R3 (or 22.3R2-S1) for the 22.3 branch; or 22.4R2 (or 22.4R1-S2) for the 22.4 branch

  1. 1. Identify the current Junos OS version on the SRX Series device using 'show version'
  2. 2. Confirm SSL Proxy and UTM Web-Filtering are enabled using 'show configuration | match ssl-proxy' and 'show configuration | match web-filtering'
  3. 3. Back up the current device configuration using 'request system configuration rescue save'
  4. 4. Download the appropriate fixed Junos OS version for your platform (22.2R3, 22.3R3, or 22.4R2) from the Juniper Networks support portal
  5. 5. Upload the new Junos OS image to the device using 'request system software add <path-to-package>' with the 'reboot' option
  6. 6. After reboot, verify the new version is running using 'show version'
  7. 7. Confirm the memory leak is resolved by monitoring jbuf memory usage over time with 'show system memory' or equivalent commands
Caveat Standard Junos OS upgrade precautions apply including potential configuration compatibility checks and service impact during the upgrade process requiring a reboot

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-2023-36831 in production — separate from our analysis above.

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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
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  • No spam, self-promotion, credentials, or personal data