iOSOperating system · Cisco
CVE-2015-0593
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 · uneditedThe Zone-Based Firewall implementation in Cisco IOS 12.4(122)T and earlier does not properly manage session-object structures, which allows remote attackers to cause a denial of service (device reload) via crafted network traffic, aka Bug ID CSCul65003.
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 confidenceThe Zone-Based Firewall in Cisco IOS 12.4(122)T and earlier contains a memory management flaw in session-object handling. Remote attackers can send specially crafted network traffic to trigger improper session structure management, causing the device to reload and resulting in denial of service.
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
= 15.4\(1.12\)t= 15.4\(1.19\)tCVSS 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
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:M/Au:N/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 checksWork through these to decide whether this CVE applies to you.
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Confirm Zone-Based Firewall is enabledRun 'show zone-pair security' or 'show policy-map type inspect zone-pair' to see if any zone-pair policies are configured and active.Affected if Any zone-pair policies exist and are actively enforcing traffic between security zones.
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Identify the Cisco IOS versionExecute 'show version' and locate the running IOS release string (e.g., 15.4(1.12)t, 12.4(122)T).Affected if The running IOS version is 15.4(1.12)t, 15.4(1.19)t, or any 12.4 version at or below 12.4(122)T.
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Verify the specific train and maintenance releaseReview the full version output from 'show version' to confirm the exact maintenance release number within the 15.4(1.)T train.Affected if The version is exactly 15.4(1.12)t or exactly 15.4(1.19)t.
The device is affected only if Zone-Based Firewall is actively configured AND the running IOS version matches one of the specific affected releases (15.4(1.12)t, 15.4(1.19)t, or 12.4 through 12.4(122)T).
Generated from the published advisory. Verify against your own configuration.
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 dataApply the Cisco IOS security update for CVE-2015-0593. If patches are unavailable for the affected IOS version, consider upgrading to a supported IOS release or temporarily disable Zone-Based Firewall if operationally feasible while implementing compensating network-level controls.
Fix this in iOS
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,128.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-0593 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-0593 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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