CVE-2017-6739 — IOS
HIGHCVE-2017-6739 is a high-severity (CVSS 8.8) Buffer Overflow vulnerability in cisco ios. It is in CISA's Known Exploited Vulnerabilities catalog (added 2022-03-03) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
A vulnerability in the SNMP implementation of could allow an authenticated, remote attacker to cause a reload of the affected system or to remotely execute code. An attacker could exploit…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2022-03-03. Federal agencies were required to remediate by 2022-03-24.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2017-6739.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2017-6739 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
Description
A vulnerability in the SNMP implementation of could allow an authenticated, remote attacker to cause a reload of the affected system or to remotely execute code. An attacker could exploit this vulnerability by sending a crafted SNMP packet to the affected device.
The vulnerability is due to a buffer overflow in the affected code area. The vulnerability affects all versions of SNMP (versions 1, 2c, and 3). The attacker must know the SNMP read only community string (SNMP version 2c or earlier) or the user credentials (SNMPv3). An exploit could allow the attacker to execute arbitrary code and obtain full control of the system or to cause a reload of the affected system.
Only traffic directed to the affected system can be used to exploit this vulnerability.
Affected Products
iosciscoios xeciscoResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every cisco ios deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2017-6739 yet — track the cisco ios advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2017-6739 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.