iOSOperating system · Cisco
CVE-2019-12665
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 · uneditedA vulnerability in the HTTP client feature of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to read and modify data that should normally have been sent via an encrypted channel. The vulnerability is due to TCP port information not being considered when matching new requests to existing, persistent HTTP connections. An attacker could exploit this vulnerability by acting as a man-in-the-middle and then reading and/or modifying data that should normally have been sent through an encrypted channel.
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 confidenceA vulnerability in the HTTP client of Cisco IOS and IOS XE Software fails to validate TCP port information when reusing persistent HTTP connections, allowing an attacker performing a man-in-the-middle attack to intercept and modify traffic that should have been encrypted.
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
= 15.6\(2\)t= fd-1.5.0CVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify the Cisco IOS/IOS XE versionExecute 'show version' and locate the firmware version in the output (look for version numbers like 15.6(2)t or fd-1.5.0)Affected if The version matches 15.6(2)t or fd-1.5.0 exactly
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Confirm HTTP client feature is enabledRun 'show running-config | include ip http client' or 'show ip http client session' to check if the HTTP client feature is configuredAffected if HTTP client sessions or HTTP client configuration appears in the output (feature is active)
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Check for persistent HTTP connection configurationRun 'show running-config | include http' and examine for persistent connection settings such as 'ip http persistent' or connection reuse parametersAffected if Persistent HTTP connection settings are present in the configuration
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Verify HTTP client is used for outbound connectionsRun 'show running-config | include (http|https) client' and check for any service policies or scripts that invoke the HTTP client for remote communicationsAffected if The device uses the HTTP client to connect to external hosts (not just serving HTTP)
You are affected if your device runs Cisco IOS version 15.6(2)t or fd-1.5.0 AND the HTTP client feature is enabled with persistent connections actively used for outbound communications.
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 relevant Cisco security update for IOS/IOS XE Software to patch the HTTP client vulnerability; ensure HTTP connections are over TLS/SSL and consider network segmentation to limit MITM attack vectors.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation3.0 h
- Testing4.0 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 $3,680.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-12665 — 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-2019-12665 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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