Threats / Cisco / CVE-2017-6739
CVE-2017-6739
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Cisco IOS and XE Software vulnerability
A buffer overflow in the SNMP subsystem of Cisco IOS and IOS XE allows authenticated remote attackers to execute arbitrary code or cause system reboot.
Verdict
Today item — known-exploited.
An authenticated remote attacker can exploit a buffer overflow in SNMP to achieve remote code execution or denial of service on affected Cisco IOS and IOS XE devices. This vulnerability has been observed in active exploitation.
CISA KEV Yes · 2022-03-035EPSS 0.10855 (verify live)6CVSS 8.83CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03).
Probability (EPSS)
EPSS 0.10855 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 8.8 (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) · Affected: Cisco, IOS and IOS XE Software. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.0, set at disclosure.
Weakness (CWE)
Mapped to CWE-119 Memory Buffer Bounds Error — weakness family: Memory safety.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 1690 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I authenticate to the SNMP service on a Cisco IOS or IOS XE device using valid credentials.
Business
Network infrastructure loses confidentiality and integrity as the attacker gains code execution on critical routing or switching equipment.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft a malicious SNMP packet that triggers a buffer overflow in the SNMP subsystem.
Business
The device becomes unavailable or unstable, disrupting network operations and potentially cascading failures across dependent systems.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary commands with the privileges of the SNMP process on the compromised device.
Business
Attackers establish persistence, exfiltrate configuration data, or pivot to other network segments from the compromised device.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by ciscoCNA
Credited with finding itNo finder is named in the public CVE record or the scanned vendor advisory — attribution scoped to the sources checked.
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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