CVE-2024-20318
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 vulnerability in the Layer 2 Ethernet services of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the line card network processor to reset, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of specific Ethernet frames that are received on line cards that have the Layer 2 services feature enabled. An attacker could exploit this vulnerability by sending specific Ethernet frames through an affected device. A successful exploit could allow the attacker to cause the ingress interface network processor to reset, resulting in a loss of traffic over the interfaces that are supported by the network processor. Multiple resets of the network processor would cause the line card to reset, resulting in a DoS condition.
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 confidenceA vulnerability in Cisco IOS XR Software's Layer 2 Ethernet services allows an adjacent, unauthenticated attacker to send specific malicious Ethernet frames that cause the ingress interface network processor to reset. Repeated resets trigger line card failure, resulting in denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/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 the product and versionRun 'show version' or check the device prompt to confirm the device runs Cisco IOS XR Software. Note the full version string.Affected if The device is running Cisco IOS XR Software and the version falls within an affected release (compare against Cisco's official advisory for version ranges).
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Check if Layer 2 Ethernet services are enabledRun 'show configuration' or 'show running-config' and search for Layer 2 related configurations such as 'interface' entries with Ethernet encapsulation, 'bridge-domain', 'l2vpn', or 'ethernet-services' configurations.Affected if Layer 2 Ethernet services (such as Ethernet interfaces, bridging, or L2VPN) are configured and active on the device.
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Verify adjacent network exposureReview the network topology and interface configurations to determine if the device has Layer 2 adjacency with untrusted or external networks. Check interface spanning-tree port roles and VLAN trunk configurations.Affected if The device has Layer 2 Ethernet interfaces connected to networks accessible to adjacent, unauthenticated attackers.
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Monitor for interface or line card resetsRun 'show logging' or 'show log' to search for recent network processor resets, line card failures, or unexpected reloads. Use 'show interface' to check for error counters.Affected if Recent network processor resets or line card failures are logged, indicating potential exploitation attempts.
The device is affected if it runs Cisco IOS XR Software with Layer 2 Ethernet services enabled and is exposed to adjacent attackers who can send malicious Ethernet frames.
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.
From vendor dataApply the Cisco patch when available. Until then, limit adjacent network access to devices with Layer 2 services enabled and monitor for unusual Ethernet frame patterns.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-20318 — 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-2024-20318 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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