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Ios XeOperating system · Cisco

CVE-2018-0315

CRITICAL · 9.8 CVSS v3.1 Published 2018-06-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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 authentication, authorization, and accounting (AAA) security services of Cisco IOS XE Software could allow an unauthenticated, remote attacker to execute arbitrary code on an affected device or cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to incorrect memory operations that the affected software performs when the software parses a username during login authentication. An attacker could exploit this vulnerability by attempting to authenticate to an affected device. A successful exploit could allow the attacker to execute arbitrary code on the affected device or cause the affected device to reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are running Cisco IOS XE Software Release Fuji 16.7.1 or Fuji 16.8.1 and are configured to use AAA for login authentication. Cisco Bug IDs: CSCvi25380.

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

A memory corruption vulnerability in Cisco IOS XE's AAA login authentication allows unauthenticated remote attackers to execute arbitrary code or cause device reloads by sending specially crafted usernames during authentication. The flaw stems from incorrect memory operations when parsing the username field.

MitigationApply Cisco's available software updates for affected IOS XE releases (16.7.1/16.8.1) or disable AAA login authentication until patching is feasible.

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 XeOperating system
Affected:= 16.7.1= 16.8.1

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
High
Availability
High

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

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

  1. Identify the Cisco IOS XE version
    Execute 'show version' on the device CLI and locate the version number in the output (typically displayed as IOS XE Version or Software Version)
    Affected if The displayed version is exactly 16.7.1 or 16.8.1
  2. Confirm AAA login authentication is enabled
    Execute 'show running-config | include aaa' and look for 'aaa authentication login' lines, or use 'show aaa sessions' to verify AAA is active
    Affected if AAA authentication for login is configured and active (the 'aaa authentication login' command points to a method list that is applied to lines or interfaces)
  3. Verify the device is accepting login connections
    Check which lines or interfaces have login authentication applied by reviewing the configuration with 'show running-config | include line' and associated login authentication settings
    Affected if Any VTY, console, or auxiliary lines are configured with login authentication that uses AAA, making the username parsing vulnerability reachable

The device is affected if it runs IOS XE version 16.7.1 or 16.8.1 AND has AAA login authentication enabled, allowing remote attackers to send specially crafted usernames during authentication attempts.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco's available software updates for affected IOS XE releases (16.7.1/16.8.1) or disable AAA login authentication until patching is feasible.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2018-0315 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
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  • No spam, self-promotion, credentials, or personal data