CVE-2024-20315
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 access control list (ACL) processing on MPLS interfaces in the ingress direction of Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to improper assignment of lookup keys to internal interface contexts. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to access resources behind the affected device that were supposed to be protected by a configured ACL.
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 confidenceThis vulnerability exists in Cisco IOS XR Software's ACL processing for MPLS interfaces in the ingress direction. The root cause is improper assignment of lookup keys to internal interface contexts, which causes the system to bypass configured ACLs. An unauthenticated remote attacker sending traffic through an affected device can access resources behind the device that should be protected by ACLs.
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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
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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Confirm Cisco IOS XR is runningExecute 'show version' or 'show inventory' to identify the device operating systemAffected if Device is not running Cisco IOS XR - not affected by this CVE
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Verify MPLS is enabled on interfacesRun 'show mpls interfaces' to list interfaces with MPLS enabledAffected if No MPLS interfaces exist on the device - the ACL bypass cannot be triggered
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Identify ACLs applied to MPLS interfaces in ingress directionUse 'show running-config interface' for each MPLS interface and look for 'in' direction ACL bindings under the interface configurationAffected if No ACLs are applied to MPLS interfaces in the ingress direction - the vulnerability has no protective ACL to bypass
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Compare installed version to affected rangesRun 'show version' to obtain the Cisco IOS XR release version, then compare against the Cisco vulnerability disclosure for CVE-2024-20315Affected if Running a version within the affected range disclosed by Cisco for this CVE
The device is affected if it runs a vulnerable Cisco IOS XR version, has MPLS-enabled interfaces, AND has ingress ACLs configured on those MPLS interfaces that should be filtering traffic.
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 IOS XR software update addressing CVE-2024-20315. Until patches are available, consider implementing additional filtering or monitoring on upstream devices to detect anomalous traffic patterns.
- Consultation6.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2024-20315 — 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-2024-20315 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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