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iOSOperating system · Cisco

CVE-2015-6263

MEDIUM · 6.3 CVSS v2.0 Published 2015-10-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Remotely reachable 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
The RADIUS client implementation in Cisco IOS 15.4(3)M2.2, when a shared RADIUS secret is configured, allows remote RADIUS servers to cause a denial of service (device reload) via malformed answers, aka Bug ID CSCuu59324.

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 vulnerability exists in the Cisco IOS RADIUS client implementation (version 15.4(3)M2.2) where malformed RADIUS server responses trigger a device reload. The vulnerability requires a configured shared RADIUS secret, allowing a compromised or malicious RADIUS server to cause denial of service by sending specially crafted answers that the IOS RADIUS client cannot properly handle.

MitigationApply the appropriate Cisco IOS software update or patch for bug CSCuu59324. As a temporary workaround, restrict which RADIUS servers can communicate with the device using ACLs, and ensure only trusted servers have access to the RADIUS infrastructure.

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
iOSOperating system
Affected:= 15.4\(3\)m2.2

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
M
Authentication
Single
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:M/Au:S/C:N/I:N/A:C

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 Cisco IOS version
    Execute 'show version' and locate the IOS release number in the output
    Affected if The version shown is exactly 15.4(3)M2.2 (note: other versions in the 15.4(3)M family may have different status)
  2. Confirm RADIUS client is configured
    Execute 'show running-config | include radius' or 'show radius' to check for RADIUS server definitions in the configuration
    Affected if RADIUS server configuration lines (such as 'radius-server host' or 'aaa group server radius') appear in the output, indicating RADIUS is enabled
  3. Verify shared RADIUS secret exists
    Examine the RADIUS configuration for a shared secret (look for 'radius-server key' or 'radius-server host x.x.x.x key' in the running config)
    Affected if A RADIUS shared secret is configured, which is required for the vulnerability to be exploitable

All three conditions must be true for the device to be affected: running Cisco IOS version 15.4(3)M2.2, having RADIUS client enabled, and possessing a configured RADIUS shared secret.

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 the appropriate Cisco IOS software update or patch for bug CSCuu59324. As a temporary workaround, restrict which RADIUS servers can communicate with the device using ACLs, and ensure only trusted servers have access to the RADIUS infrastructure.

Fix this in iOS Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2015-6263 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