dbcve.org
Cumulus LinuxOperating system · Nvidia

CVE-2023-25525

HIGH · 7.5 CVSS v3.1 Published 2023-09-20
Fix available
A fix is available. Upgrade to 5.6.0 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable 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
NVIDIA Cumulus Linux contains a vulnerability in forwarding where a VxLAN-encapsulated IPv6 packet received on an SVI interface with DMAC/DIPv6 set to the link-local address of the SVI interface may be incorrectly forwarded. A successful exploit may lead to information disclosure.

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

NVIDIA Cumulus Linux has a forwarding vulnerability where VxLAN-encapsulated IPv6 packets received on an SVI interface with the destination MAC and IPv6 address set to the interface's link-local address are incorrectly forwarded. This mishandling can cause information disclosure by allowing unauthorized packet forwarding.

MitigationApply the vendor-supplied patch or upgrade to a fixed Cumulus Linux version. Restrict VxLAN traffic at network boundaries and monitor for anomalous IPv6 forwarding behavior until the patch is deployed.

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
Cumulus LinuxOperating system
Affected:< 5.6.0

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
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Cumulus Linux version
    Run 'cat /etc/os-release' or 'net show version' to retrieve the installed Cumulus Linux version number
    Affected if The version shown is less than 5.6.0 (for example, 5.5.0, 5.4.0, etc.)
  2. Confirm VxLAN is configured
    Run 'net show interface' or inspect /etc/network/interfaces for any 'vxlan' type interfaces
    Affected if VxLAN interfaces are present and configured in the network
  3. Check for SVI interfaces with IPv6 link-local addresses
    Run 'ip -6 addr show' or 'net show interface' to list all interfaces and their IPv6 addresses, noting any SVI interfaces that have link-local addresses assigned
    Affected if SVI interfaces exist with IPv6 link-local addresses (fe80::/10 prefix)
  4. Monitor for VxLAN-encapsulated IPv6 traffic
    Use packet capture on a VxLAN interface (for example, using 'tcpdump -i vxlan<id> -nn -v ip6') to observe if VxLAN-encapsulated IPv6 packets are being received
    Affected if VxLAN-encapsulated IPv6 packets are being forwarded to the SVI interface with destination MAC and IPv6 matching the link-local address

You are affected if running Cumulus Linux version 5.5.x or earlier AND you have VxLAN configured with SVI interfaces that handle IPv6 link-local traffic.

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 5.6.0 or later
Fixed in 5.6.0
Interim mitigation

Apply the vendor-supplied patch or upgrade to a fixed Cumulus Linux version. Restrict VxLAN traffic at network boundaries and monitor for anomalous IPv6 forwarding behavior until the patch is deployed.

Recommended fix High confidence

Cumulus Linux 5.6.0 or later

  1. 1. Back up the current Cumulus Linux configuration using 'sudo cp -r /etc/network/interfaces /etc/network/interfaces.bak' and any other critical config files
  2. 2. Verify current version with 'cat /etc/cumulus/box-version' or 'cumulus-version' to confirm upgrade is needed
  3. 3. Download the Cumulus Linux 5.6.0 or later disk image from the NVIDIA Cumulus portal (nvidia.custhelp.com)
  4. 4. Transfer the image to the switch and verify its checksum
  5. 5. Install the new image using 'onie-install -a -i <path-to-image>' followed by 'reboot' to initiate the install
  6. 6. After the switch reboots, verify the upgrade was successful by running 'cumulus-version' or 'cat /etc/cumulus/box-version'
  7. 7. Restore any custom configuration files from the backup and verify network services are operating normally
Caveat Review NVIDIA Cumulus Linux 5.6.0 release notes for any configuration or feature changes compared to your current version, as some legacy features may have been deprecated

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

Fix this in Cumulus Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
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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-2023-25525 in production — separate from our analysis above.

No notes yet

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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