dbcve.org
iOSOperating system · Cisco

CVE-2008-3803

MEDIUM · 5.1 CVSS v2.0 Published 2008-09-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
60/100
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 "logic error" in Cisco IOS 12.0 through 12.4, when a Multiprotocol Label Switching (MPLS) VPN with extended communities is configured, sometimes causes a corrupted route target (RT) to be used, which allows remote attackers to read traffic from other VPNs in opportunistic circumstances.

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 · moderate confidence

A logic error in Cisco IOS 12.0 through 12.4 causes corrupted route targets to be used when MPLS VPNs with extended communities are configured, potentially allowing cross-VPN traffic leakage in opportunistic circumstances.

MitigationUpgrade to a Cisco IOS version beyond 12.4 that addresses this vulnerability, or implement additional route filtering and RT validation controls at PE routers to detect corrupted route targets.

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:= 12.0s= 12.0sx= 12.0sz

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
High
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:H/Au:N/C:P/I:P/A:P

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' on the IOS device CLI to retrieve the running software version
    Affected if The version displayed falls within the 12.0 through 12.4 range (including 12.0S, 12.0SX, 12.0SZ trains)
  2. Confirm MPLS VPN is configured
    Execute 'show ip vrf' or 'show running-config | include vrf' to list configured VRFs
    Affected if MPLS VPNs (VRF instances) are configured on the device
  3. Verify extended communities are in use
    Execute 'show ip vrf detail' or examine VRF configuration for 'route-target' statements that include extended community attributes
    Affected if VRFs are configured with route-target extended communities
  4. Inspect route-target assignment
    Execute 'show ip bgp vpnv4 all tags' or 'show bgp vpnv4 unicast vrf NAME' to examine exported route targets and compare against intended configuration
    Affected if Exported route targets do not match the configured intended values, indicating potential corruption

The environment is affected if running Cisco IOS 12.0-12.4 with MPLS VPNs configured that use extended communities, where route-target values appear corrupted or mismatched from intended configuration.

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

Upgrade to a Cisco IOS version beyond 12.4 that addresses this vulnerability, or implement additional route filtering and RT validation controls at PE routers to detect corrupted route targets.

Fix this in iOS Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2008-3803 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2008-3803 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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