dbcve.org
Ios XrOperating system · Cisco

CVE-2024-20390

MEDIUM · 5.3 CVSS v3.1 Published 2024-09-11
Fix available
A fix is available. Upgrade to 24.1.2 or later.
See remediation →
62/100
Remediation priority · Elevated
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
A vulnerability in the Dedicated XML Agent feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) on XML TCP listen port 38751. This vulnerability is due to a lack of proper error validation of ingress XML packets. An attacker could exploit this vulnerability by sending a sustained, crafted stream of XML traffic to a targeted device. A successful exploit could allow the attacker to cause XML TCP port 38751 to become unreachable while the attack traffic persists.

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

The vulnerability exists in Cisco IOS XR Software's Dedicated XML Agent feature. It stems from improper error validation of incoming XML packets on TCP port 38751, allowing an unauthenticated remote attacker to send crafted XML traffic that renders the XML TCP port unreachable, causing denial of service while attack traffic persists.

MitigationApply the Cisco patch when available; meanwhile, restrict access to TCP port 38751 via ACLs or disable the XML Agent if not required, and implement rate-limiting on the affected port.

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
Ios XrOperating system
Affected:< 24.1.2

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
None
Integrity
None
Availability
Low

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

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 device is running Cisco IOS XR
    Use 'show version' or 'admin show version' command to confirm the operating system is Cisco IOS XR and note the exact version number.
    Affected if The device runs Cisco IOS XR with a version lower than 24.1.2
  2. Verify the Dedicated XML Agent is enabled
    Check if the XML Agent feature is active by examining the configuration with 'show xml agent' or reviewing the running configuration for 'xml agent' settings.
    Affected if The Dedicated XML Agent is enabled and listening on the system
  3. Confirm TCP port 38751 is open and listening
    Use 'show tcp brief' or 'show listeners' commands to check if the XML Agent is bound to TCP port 38751, or run a port scan against the device on port 38751 from an allowed network.
    Affected if TCP port 38751 is open and accepting connections
  4. Review for recent XML service disruptions
    Check system logs and use 'show log' or 'show logging' to look for errors related to XML agent, port 38751, or service availability issues.
    Affected if Logs show repeated XML service failures or port 38751 errors

A system is affected if it runs Cisco IOS XR version below 24.1.2 with the Dedicated XML Agent enabled and TCP port 38751 exposed, rendering the XML service vulnerable to denial of service from crafted 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 24.1.2 or later
Fixed in 24.1.2
Interim mitigation

Apply the Cisco patch when available; meanwhile, restrict access to TCP port 38751 via ACLs or disable the XML Agent if not required, and implement rate-limiting on the affected port.

Recommended fix High confidence

Cisco IOS XR 24.1.2 or later

  1. Identify the current Cisco IOS XR version running on the device using 'show version'
  2. Schedule a maintenance window following Cisco's standard upgrade procedures
  3. Download Cisco IOS XR version 24.1.2 or later from Cisco's software download center
  4. Upgrade the device using the appropriate install method (e.g., 'install add' and 'install activate' commands)
  5. After upgrade completes, verify the XML agent service is operational on TCP port 38751 using 'show xml agent'
  6. Confirm the device is no longer vulnerable by verifying the running version is >= 24.1.2

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

Fix this in Ios Xr Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.

Scan for this in your stack

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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-2024-20390 in production — separate from our analysis above.

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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