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Debian LinuxOperating system · Debian

CVE-2022-2928

MEDIUM · 6.5 CVSS v3.1 Published 2022-10-07
Fix available
A fix is available. Upgrade to after 4.4.3 or later.
See remediation →
70/100
Remediation priority · Elevated
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
In ISC DHCP 4.4.0 -> 4.4.3, ISC DHCP 4.1-ESV-R1 -> 4.1-ESV-R16-P1, when the function option_code_hash_lookup() is called from add_option(), it increases the option's refcount field. However, there is not a corresponding call to option_dereference() to decrement the refcount field. The function add_option() is only used in server responses to lease query packets. Each lease query response calls this function for several options, so eventually, the reference counters could overflow and cause the server to abort.

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

In ISC DHCP servers 4.4.0-4.4.3 and 4.1-ESV-R1 through 4.1-ESV-R16-P1, the add_option() function increments reference counts via option_code_hash_lookup() but never decrements them with option_dereference(). Since add_option() is only used in server responses to lease query packets, repeated lease query responses cause reference counters to increment unbounded until overflow, triggering server abort.

MitigationApply vendor patches to ISC DHCP servers; until patched, consider restricting or filtering lease query packet access to reduce exposure to this flaw.

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
Debian LinuxOperating system
Affected:= 10.0
FedoraOperating system
Affected:= 35= 36= 37
DhcpApplication
Affected:>= 4.4.0, <= 4.4.3= 4.1-esv

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

CVSS:3.1/AV:A/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 ISC DHCP server version
    Run 'dhcpd -version' or check the package version via 'rpm -q dhcp' (Fedora) or 'dpkg -l isc-dhcp-server' (Debian)
    Affected if Version matches 4.4.0 through 4.4.3, or 4.1-ESV-R1 through 4.1-ESV-R16-P1
  2. Confirm lease query feature is in use
    Check dhcpd.conf for 'lease-query' statement or inspect network traffic for DHCP lease query packets (UDP port 67)
    Affected if Lease query is enabled in configuration or lease query packets are being processed
  3. Check for server crash or abort events
    Review system logs (/var/log/messages, /var/log/syslog, or journalctl -u isc-dhcp-server) for unexpected server termination or abort messages
    Affected if Server has crashed or aborted with reference count overflow errors
  4. Inspect running dhcpd process
    Use 'ps aux | grep dhcpd' to verify the server process is running and monitor for frequent restarts
    Affected if Server process is unstable, frequently restarting, or not running

Environment is affected if ISC DHCP server version 4.4.0-4.4.3 or 4.1-ESV-R1 through 4.1-ESV-R16-P1 is installed and lease query feature is enabled or being used, potentially causing server instability or crashes.

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 a release after 4.4.3
Interim mitigation

Apply vendor patches to ISC DHCP servers; until patched, consider restricting or filtering lease query packet access to reduce exposure to this flaw.

Recommended fix Moderate confidence

ISC DHCP 4.4.4 or later (4.4.x series); ISC DHCP 4.1-ESV-R16-P2 or later (4.1-ESV series)

  1. 1. Identify the currently installed ISC DHCP server version using: `dhcpd -v` or `rpm -q dhcp` / `dpkg -l isc-dhcp-server`
  2. 2. For Debian 10.0 users: Update the package repository and upgrade using: `apt-get update && apt-get install isc-dhcp-server`
  3. 3. For Fedora 35-37 users: Update the system and upgrade the dhcp package using: `dnf update dhcp`
  4. 4. After upgrade, verify the new version is running: `dhcpd -v`
  5. 5. Restart the DHCP service to apply changes: `systemctl restart dhcpd` (for server) or `systemctl restart dhcpd-client` (for client)
Caveat Minimal risk - ISC patch releases are typically backward-compatible; however, always test in a staging environment before production deployment

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2022-2928 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