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iOSOperating system · Cisco

CVE-2007-0917

MEDIUM · 6.4 CVSS v2.0 Published 2007-02-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
73/100
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
The Intrusion Prevention System (IPS) feature for Cisco IOS 12.4XE to 12.3T allows remote attackers to bypass IPS signatures that use regular expressions via fragmented packets.

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 IPS feature (versions 12.4XE to 12.3T), where fragmented packets can be used to bypass IPS signatures that rely on regular expression matching. An attacker can evade detection by fragmenting malicious traffic, allowing it to pass through the IPS without being matched against signatures.

MitigationApply the appropriate Cisco IOS software update that addresses this IPS evasion vulnerability. After updating, verify that IPS signatures are properly detecting both fragmented and non-fragmented traffic.

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:= 12.3t= 12.3xq= 12.3xr= 12.3xs= 12.3xw= 12.3xx= 12.3xy= 12.3ya= 12.3yd= 12.3yg= 12.3yh= 12.3yi

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
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
None

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

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 version
    Use 'show version' command on the Cisco device to obtain the installed IOS version number
    Affected if The version matches any of these: 12.3t, 12.3xq, 12.3xr, 12.3xs, 12.3xw, 12.3xx, 12.3xy, 12.3ya, 12.3yd, 12.3yg, 12.3yh, or 12.3yi
  2. Confirm IPS feature is enabled
    Use 'show ips' or 'show ip ips' command to verify the Cisco IOS IPS feature is active and signatures are loaded
    Affected if IPS is enabled and signatures are loaded on the device
  3. Check if regex-based signatures are in use
    Use 'show ip ips signatures' or 'show ips sig' to list loaded signatures and check for signatures that rely on regular expression (regex) pattern matching
    Affected if The device has regex-based signatures loaded and active

The device is affected if it runs an affected Cisco IOS version (12.3t through 12.3yi) AND has the IPS feature enabled with regex-based signatures loaded.

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 that addresses this IPS evasion vulnerability. After updating, verify that IPS signatures are properly detecting both fragmented and non-fragmented traffic.

Fix this in iOS 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 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-2007-0917 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