iOSOperating system · Cisco
CVE-2017-6743
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 Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE Software contains multiple vulnerabilities that could allow an authenticated, remote attacker to remotely execute code on an affected system or cause an affected system to reload. An attacker could exploit these vulnerabilities by sending a crafted SNMP packet to an affected system via IPv4 or IPv6. Only traffic directed to an affected system can be used to exploit these vulnerabilities. The vulnerabilities are due to a buffer overflow condition in the SNMP subsystem of the affected software. The vulnerabilities affect all versions of SNMP - Versions 1, 2c, and 3. To exploit these vulnerabilities via SNMP Version 2c or earlier, the attacker must know the SNMP read-only community string for the affected system. To exploit these vulnerabilities via SNMP Version 3, the attacker must have user credentials for the affected system. A successful exploit could allow the attacker to execute arbitrary code and obtain full control of the affected system or cause the affected system to reload. Customers are advised to apply the workaround as contained in the Workarounds section below. Fixed software information is available via the Cisco IOS Software Checker. All devices that have enabled SNMP and have not explicitly excluded the affected MIBs or OIDs should be considered vulnerable. There are workarounds that address these vulnerabilities.
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 confidenceBuffer overflow vulnerability in Cisco IOS/IOS XE SNMP subsystem allows authenticated remote attackers to execute arbitrary code or cause system reload via crafted SNMP packets. Exploitation requires valid SNMP community string (v1/2c) or user credentials (v3). Affects all SNMP versions.
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
>= 12.0, <= 12.4>= 15.0, <= 15.6
Ios XeOperating system
>= 2.2.0, <= 3.17CVSS 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
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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 Cisco product typeRun 'show version' and look for 'IOS' or 'IOS XE' in the output to identify the software typeAffected if The device runs Cisco IOS or IOS XE software
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Check if SNMP is enabledRun 'show snmp' or 'show running-config | include snmp' to see if SNMP is configuredAffected if SNMP is enabled (any community string or SNMPv3 user configured)
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Identify the installed versionRun 'show version' and locate the version number (for IOS XE, also run 'show version | include Version' to get the detailed release)Affected if Version falls within >= 12.0 <= 12.4, >= 15.0 <= 15.6 for IOS, or >= 2.2.0 <= 3.17 for IOS XE
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Check SNMP access configurationRun 'show snmp group' or examine the running-config for SNMP community strings or SNMPv3 user configurationsAffected if SNMP v2c community strings or SNMP v3 credentials are configured and accessible from the network
The device is affected if it runs a vulnerable Cisco IOS (12.0-12.4 or 15.0-15.6) or IOS XE (2.2.0-3.17) version AND has SNMP enabled with v2c community strings or SNMPv3 credentials accessible to attackers.
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.
dbcve · scopedApply Cisco-provided workarounds (such as SNMP access lists or disabling affected MIBs) or deploy fixed software via Cisco IOS Software Checker. Disable SNMP if not required.
iOS 12.5+ / iOS 15.7+ / IOS XE 3.18+ (use Cisco Software Checker for exact per-platform recommendation)
- 1. Identify the exact Cisco iOS or IOS XE version currently running on the affected device using 'show version' command
- 2. Use the Cisco IOS Software Checker (https://tools.cisco.com/security/center/selectIOSVersion.x) to find the recommended fixed release for your specific version and platform
- 3. For iOS versions 12.0-12.4: Upgrade to 12.5 or later (12.5 is the first fixed release in the 12.x train)
- 4. For iOS versions 15.0-15.6: Upgrade to 15.7 or later
- 5. For IOS XE versions 2.2.0-3.17: Upgrade to 3.18 or later
- 6. After upgrading, verify the new version using 'show version' and confirm SNMP functionality is working as expected
- 7. As an additional mitigation, restrict SNMP access using ACLs: configure 'snmp-server community <string> ro <acl-number>' with an ACL that limits SNMP source addresses to authorized management stations only
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in iOS
Exploited in the wild — priority engagement
- Consultation4.0 h
- Implementation8.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-6743 — 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-2017-6743 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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