CVE-2023-3748
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 · uneditedA flaw was found in FRRouting when parsing certain babeld unicast hello messages that are intended to be ignored. This issue may allow an attacker to send specially crafted hello messages with the unicast flag set, the interval field set to 0, or any TLV that contains a sub-TLV with the Mandatory flag set to enter an infinite loop and cause a denial of service.
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 confidenceFRRouting contains a denial of service vulnerability in its babeld routing daemon where parsing specially crafted unicast hello messages with specific malformed fields (unicast flag set, interval=0, or TLV with Mandatory sub-TLV) triggers an infinite loop, causing the routing process to hang.
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< 8.5CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify if babeld is runningRun 'ps aux | grep babeld' or 'systemctl status babeld' to see if the babeld process is activeAffected if babeld process is running and the version is below 8.5
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Check installed FRRouting versionRun 'frr -v' or 'rpm -q frr' (RHEL) or 'dpkg -l frr' (Debian) to retrieve the installed package versionAffected if version is below 8.5 and babeld is enabled
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Verify babel protocol configurationRun 'vtysh -c "show babel interface"' to list interfaces with babel enabledAffected if any interface has babel protocol configured and the FRRouting version is vulnerable
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Check babeld process statusRun 'vtysh -c "show babel neighbor"' or monitor babeld process with 'top'/'htop' for hung stateAffected if babeld process is hung or unresponsive and was processing unicast hello packets
A defender is affected if babeld is running on FRRouting version below 8.5 and has babel protocol enabled on any network interface, as malformed unicast hello messages can trigger the infinite loop.
Generated from the published advisory. Verify against your own configuration.
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 · scoped8.5
Apply the relevant FRRouting security patch or upgrade to a version where this vulnerability has been addressed; additionally, network-level filtering of malformed babel packets can provide interim protection.
FRRouting 8.5 or later
- 1. Backup current FRRouting configuration files (typically in /etc/frr/ or /usr/local/etc/frr/)
- 2. Stop the FRRouting services (frr, zebra, babeld, or frr.service depending on your system)
- 3. Update your package repository to ensure you have access to the latest packages
- 4. Install FRRouting version 8.5 or later using your system's package manager (e.g., apt-get install frr, yum install frr, or dnf install frr)
- 5. Verify the installed version matches or exceeds 8.5 (frr -v or frrctl version)
- 6. Restore or verify your configuration files are compatible
- 7. Start FRRouting services
- 8. Monitor babeld daemon logs for any errors or startup issues
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing5.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-3748 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-3748 in production — separate from our analysis above.
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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- Version or environment caveats, and links to real fixes
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