CVE Intelligence
CISA KEV High Memory corruption

CVE-2017-6740 — Cisco IOS and IOS XE Software SNMP Remote Code Execution Vulnerability

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.

Published Jul 17, 2017 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: cisco

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · Mar 3, 2022
How the score was calculated
  • Confirmed exploitation (CISA KEV)+35
  • EPSS 11.1% (30-day exploitation probability)+14
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Confirmed
CISA KEV, listed Mar 3, 2022
EPSS FIRST
11.1%
ahead of 96% of scored CVEs · Oct 14, 2026
Affects
Cisco
Ios and 2 more
CVSS base
8.8
High · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Active
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: Mar 24, 2022 — passed 1666 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Cisco Ios, Cisco Ios Xe, IntelliShield Universal Product).
  2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. EPSS ahead of 96% of scored CVEs: prioritize it in the patch queue.
  5. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Cisco Ios version 12.2(18)SXF11version 15.0(2)EX8version 15.0(2)EX2version 15.0(1)EXversion 15.0(2)SG11aversion 15.0(2)XOversion 15.0(1)XOversion 15.0(1)XO1
and 64 more version 12.2(33)STE0version 12.2(28)ZXversion 15.0(2)EX10version 12.2(18)SXF2version 12.2(18)SXF13version 12.2(18)SXF9version 12.2(18)SXF12aversion 12.2(18)SXF14version 12.2(18)SXF17aversion 12.2(18)SXF7version 12.2(18)SXF16version 15.1(3)SVDversion 15.1(3)SVJ2version 15.1(3)SVGversion 15.1(3)SVEversion 15.1(3)SVF1version 15.1(3)SVFversion 15.1(3)SVD2version 15.1(3)SVD1version 12.2(14)ZAversion 15.1(3)SVB2version 15.1(3)SVB1version 15.1(3)MRA4version 15.1(3)MRA3version 15.1(2)SY9version 15.0(2)EX12version 15.0(2)EX13version 15.0(2)EX11version 12.2(17d)SXB6version 12.2(17d)SXB8version 12.2(17d)SXB10version 12.2(17d)SXB5version 12.2(17d)SXB3version 12.2(17d)SXB2version 12.2(17d)SXB4version 12.2(17d)SXB7version 12.2(17d)SXB11version 12.2(18)SXF8version 12.2(29)SV2version 12.2(25)SE2version 12.2(14)ZA7version 12.2(14)ZA6version 12.2(14)ZA4version 12.2(14)ZA5version 12.2(14)ZA2version 12.2(14)ZA3version 12.2(17d)SXB1version 12.2(18)SXF10aversion 12.2(18)SXF12version 12.2(18)SXF17version 12.2(18)SXF3version 12.2(18)SXF15aversion 12.2(18)SXF4version 12.2(18)SXF17bversion 12.2(18)SXF10version 12.2(18)SXF15version 12.2(18)SXF6version 12.2(18)SXF5version 12.2(18)SXFversion 12.2(18)SO2version 12.2(18)SO3version 12.2(18)SO1version 12.2(17d)SXB9version 12.2(17d)SXB11a
Vulnerable CVE Program (cve.org) e CISA ADP
Cisco Ios ≥ 15.0 and ≤ 15.6≥ 12.0 and ≤ 12.4 Vulnerable NIST National Vulnerability Database
Cisco Ios Xe ≥ 2.2.0 and ≤ 3.17 Vulnerable NIST National Vulnerability Database
IntelliShield Universal Product version N/A Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.8 CVSS 3.1 High 2.8 5.9 nvd@nist.gov via NIST National Vulnerability Database
8.8 CVSS 3.0 High 2.8 5.9 psirt@cisco.com via NIST National Vulnerability Database
8.8 CVSS 3.0 High — — GitHub, Inc. via GitHub Security Advisories
8.8 CVSS 3.0 High — — cisco via CVE Program (cve.org) e CISA ADP
9.0 CVSS 2.0 High 8.0 10.0 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-119 · Buffer Errors (Improper Restriction of Operations within Memory Bounds)

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed
Mar 3, 2022
Federal deadline
Mar 24, 2022
passed 1666 day(s) ago
Ransomware use
Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 11.10%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
  • Hunt retroactively in logs from before Mar 3, 2022 (KEV listing): exploitation may have started earlier.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · cisco/ios, cisco/ios xe
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 13, 2026
  • Affected products added · cisco/ios, intellishield/universal product
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • CVSS changed · 8.8
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Added to CISA KEV (detected)
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • Record created in this database
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • 2022
  • Added to CISA KEV catalog
    Mar 2, 2022 · CISA
  • 2017
  • CVE published
    Jul 17, 2017 · cisco

Source activity

Repeated readings are counted rather than listed.

  • 3× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

7 on the record

Elsewhere on this site

Cisco
every CVE for this vendor
2022-03
what else CISA listed that month
Memory corruption
same class
CWE-119
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-20301 A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as… Aug 5, 2026
  • CVE-2026-20273 Improper Input Validation in Cisco Ios Xe Aug 5, 2026
  • CVE-2026-20272 Injection in Cisco Ios Xe Aug 5, 2026
  • CVE-2026-20271 As part of Cisco's ongoing commitment to proactive security and product quality, the… Aug 5, 2026
  • CVE-2026-20269 As part of Cisco's ongoing commitment to proactive security and product quality, the… Aug 5, 2026
  • CVE-2026-20270 As part of Cisco's ongoing commitment to proactive security and product quality, the… Aug 5, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2017-6740 is "Cisco IOS and IOS XE Software SNMP Remote Code Execution Vulnerability", rated High. It affects Ios (Cisco); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 8.8 describes technical severity. EPSS 11.10% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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