dbcve.org
Enterprise LinuxOperating system · Redhat

CVE-2023-38469

MEDIUM · 5.5 CVSS v3.1 Published 2023-11-02
Fix available
A fix is available. Upgrade to 0.9 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
A vulnerability was found in Avahi, where a reachable assertion exists in avahi_dns_packet_append_record.

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 · moderate confidence

A reachable assertion in avahi_dns_packet_append_record() in the Avahi mDNS/DNS-SD daemon can be triggered by specially crafted DNS packets, leading to a denial of service via daemon crash. The assertion failure indicates insufficient input validation in the DNS record appending logic.

MitigationUpdate Avahi to the latest version containing the patch. If patching is not immediately feasible, restrict network access to the mDNS service (port 5353/UDP) via firewall rules to limit exposure to adjacent network attackers.

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
Enterprise LinuxOperating system
Affected:= 8.0= 9.0
AvahiApplication
Affected:< 0.9

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. Verify Avahi is installed
    Run 'rpm -qa | grep -i avahi' (RHEL) or 'dpkg -l | grep -i avahi' (Debian-based) to list installed Avahi packages
    Affected if No Avahi packages are found, meaning the product is not installed and not affected
  2. Check installed Avahi version
    Run 'rpm -q avahi' (RHEL) or 'dpkg -s avahi-daemon' (Debian) to get the exact version number, then compare to the affected range (RHEL 8.0, 9.0; Avahi < 0.9)
    Affected if The installed version falls within RHEL 8.0, RHEL 9.0, or is earlier than version 0.9
  3. Confirm Avahi daemon is running
    Run 'systemctl status avahi-daemon' or 'ps aux | grep avahi-daemon' to check if the Avahi daemon process is active
    Affected if The daemon is running and exposed to network (see next check)
  4. Check if mDNS port 5353/UDP is exposed
    Run 'ss -ulnp | grep 5353' or 'netstat -ulnp | grep 5353' to see if port 5353/UDP is listening, indicating the mDNS service is network-accessible
    Affected if Port 5353/UDP is listening and accessible from network, allowing specially crafted DNS packets to reach the service

A system is affected if it runs Avahi with version in the affected range (RHEL 8.0, 9.0, or < 0.9), the daemon is running, and port 5353/UDP is exposed to network attackers.

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 0.9 or later
Fixed in 0.9
Interim mitigation

Update Avahi to the latest version containing the patch. If patching is not immediately feasible, restrict network access to the mDNS service (port 5353/UDP) via firewall rules to limit exposure to adjacent network attackers.

Recommended fix Moderate confidence

Red Hat Enterprise Linux 8: avahi-0.8-19.el8 or later | Red Hat Enterprise Linux 9: avahi-0.9-1.el9 or later (consult access.redhat.com for exact RHSA)

  1. Ensure your system is registered with Red Hat Subscription Management or Satellite
  2. Run 'sudo dnf check-update' to check for available avahi updates
  3. Run 'sudo dnf update avahi' to apply the latest avahi package that includes the fix for CVE-2023-38469
  4. After updating, verify the installed version with 'rpm -q avahi'
  5. Reboot services or the system if required to ensure the new version is fully loaded
  6. Alternatively, for immediate deployment across multiple systems, use 'sudo dnf update -y avahi' in your automation/management tools
Caveat Minimal risk; this is a security bugfix in the Avahi mDNS daemon. Ensure no custom Avahi configurations rely on behavior that triggered the assertion. After update, verify mDNS/service discovery functionality remains operational.

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

Fix this in Enterprise Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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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-2023-38469 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data