Improper Access ControlWeakness · CWE-284

CVE-2025-0650

HIGH · 8.1 CVSS v3.1 Published 2025-01-23

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

90/100

Remediation priority · Urgent

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

A flaw was found in the Open Virtual Network (OVN). Specially crafted UDP packets may bypass egress access control lists (ACLs) in OVN installations configured with a logical switch with DNS records set on it and if the same switch has any egress ACLs configured. This issue can lead to unauthorized access to virtual machines and containers running on the OVN network.

Technical summary

dbcve analysis · high confidence

OVN's egress ACL enforcement can be bypassed by specially crafted UDP packets when a logical switch has both DNS records and egress ACLs configured. The ACL engine fails to properly evaluate UDP traffic against the configured egress rules, allowing unauthorized outbound access from VMs and containers.

MitigationApply OVN patches or upgrade to a fixed version when available. In the interim, review and tighten network segmentation at underlying infrastructure layers, and consider adding complementary firewall rules on hypervisors as a defense-in-depth measure.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown

From the vector

Attack vector: Network
Complexity: High
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

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

Am I affected?

dbcve checks

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

Identify OVN version in use

Run 'ovn-nbctl --version' or check the OVN package version installed on the OVN controller/central node (e.g., dpkg -l | grep ovn or rpm -q openvswitch-ovn)

Affected if The installed OVN version is lower than the first fixed version when released
List logical switches with DNS records

Run 'ovn-nbctl list logical_switch' to see all logical switches, then for each switch run 'ovn-nbctl get logical_switch <switch> external_ids' to check for DNS-related external_ids or use 'ovn-nbctl list dns' to list DNS records

Affected if Any logical switch has DNS records configured (found in the dns table or via external_ids containing dns information)
Identify egress ACLs on logical switches

Run 'ovn-nbctl acl-list <logical_switch>' for each logical switch, or query all ACLs with 'ovn-nbctl list acl' and filter for direction='from-lport' (egress) rules

Affected if Any logical switch has egress ACLs configured (ACLs with from-lport direction)
Determine vulnerable configuration combination

Cross-reference the logical switches identified in step 2 (with DNS) against step 3 (with egress ACLs). Identify any logical switch that appears in both lists.

Affected if A logical switch has BOTH DNS records AND egress ACLs configured - this is the vulnerable configuration

You are affected if your OVN deployment has at least one logical switch with both DNS records and egress ACLs configured, combined with a vulnerable OVN version.

Generated from the published advisory. Verify against your own configuration.

Remediation

From vendor data

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Apply OVN patches or upgrade to a fixed version when available. In the interim, review and tighten network segmentation at underlying infrastructure layers, and consider adding complementary firewall rules on hypervisors as a defense-in-depth measure.

Have this fixed Scoped from the published advisory

Consultation4.0 h
Implementation8.0 h
Testing6.0 h
Review / QA2.0 h

20.0 hours of engineering $3,500

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Scan for this in your stack

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-0650 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2025-0650?

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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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

At a glance

A fix existsA vendor remedy is published

Severity 8.1 High

Exploit likelihood EPSS, next 30 days 0.9%

Remediation

A high-priority fix

Have this fixed 20 hrs · Moderate

Typical engagement from $3,500

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2025-0650 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

CVSS breakdown

Am I affected?

Remediation

References