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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 24 Mar 2022.
iOSOperating system · Cisco

CVE-2017-6744

HIGH · 8.8 CVSS v3.1 Published 2017-07-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable 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 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 confidence

Buffer overflow vulnerabilities in the SNMP subsystem of Cisco IOS and IOS XE Software allow authenticated remote attackers to execute arbitrary code or cause system reloads via crafted SNMP packets. Exploitation requires either knowledge of the SNMP community string (for v1/v2c) or valid SNMPv3 user credentials. The vulnerabilities affect all SNMP versions and can be triggered by traffic directed to the affected system over IPv4 or IPv6.

MitigationApply Cisco's available workarounds (SNMP access controls, ACLs, disabling vulnerable MIBs/OIDs) and/or update to the fixed software version via the Cisco IOS Software Checker. Restrict SNMP access to trusted management networks and change community strings.

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:= 12.2\(33\)sxi= 12.2\(33\)sxi1= 12.2\(50\)se= 12.2\(50\)se1= 12.2\(50\)se2= 12.2\(50\)se3= 12.2\(50\)se4= 12.2\(50\)se5= 12.2\(50\)sg= 12.2\(50\)sg1= 12.2\(50\)sg2= 12.2\(50\)sg3

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Cisco IOS version
    Execute 'show version' on the device CLI and locate the version string (e.g., 12.2(50)SE5)
    Affected if The version matches one of: 12.2(33)sxi, 12.2(33)sxi1, 12.2(50)SE, 12.2(50)SE1, 12.2(50)SE2, 12.2(50)SE3, 12.2(50)SE4, 12.2(50)SE5, 12.2(50)SG, 12.2(50)SG1, 12.2(50)SG2, or 12.2(50)SG3
  2. Confirm SNMP is enabled
    Run 'show snmp' or 'show running-config | include snmp-server' to check for SNMP configuration
    Affected if SNMP is configured and the SNMP server process is running (any 'snmp-server' commands present in configuration)
  3. Check SNMP community string configuration
    Run 'show running-config | include community' to view configured community strings
    Affected if Any SNMP community string (v1/v2c) is configured, as the vulnerability requires valid credentials to exploit

The device is affected if it runs any of the listed iOS versions AND has SNMP enabled with a configured community string or SNMPv3 user credentials.

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 Cisco's available workarounds (SNMP access controls, ACLs, disabling vulnerable MIBs/OIDs) and/or update to the fixed software version via the Cisco IOS Software Checker. Restrict SNMP access to trusted management networks and change community strings.

Fix this in iOS Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2017-6744 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