What is CVE-2017-6736?A high-severity flaw criminals are using now.
CVE-2017-6736 is a high-severity flaw (CVSS 8.8) in IOS from Cisco, published on 17 July 2017. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 70%. If you run an affected version, patch it first.
Published 17 July 2017. Record last updated 22 October 2025. We keep this page's data up to date.
What is CVE-2017-6736? In plain terms.
It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.
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.
What kind of flaw is it?
- CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
How an attack on it works
Read straight from its severity rating, translated out of the shorthand.
- Where an attacker can beAnywhere on the internet
- How hard it is to pull offEasy: no special conditions
- Login needed firstAn ordinary user account
- Does someone have to clickNo, nobody has to do anything
- What an attacker getsCan read data, change data and take it offline
Severity vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Is CVE-2017-6736 being exploited? Yes.
Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 70%.
Timeline
- Published
- Record last updated
- Exploit likelihood fell
CVE-2017-6736 scores 85. Action: Emergency patch.
We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:
- Evidence it is being exploitedBiggest factor
- How severe it isStrong factor
- How widely exposed it isSmaller factor
- Threat activity around itSmaller factor
85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.
When CVE-2017-6736 matches software you track, it lands in your list with its score and the reasons behind it.
See your own ranked list →Who is affected by CVE-2017-6736? 2 products.
The published record lists 2 products from 1 vendor. If you run one of these, check your version, then go to the fix below.
How do I fix CVE-2017-6736? Four steps.
- Check whether you run itCompare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
- Apply the vendor’s fixInstall the update named in the vendor’s advisory. We’ve put the advisory first in the list.
- If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
- Check it wasn’t used before you patchedBecause criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.
References
7 linksDoes CVE-2017-6736 affect you? We'll keep checking.
Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.
- Tell us what you runPick your software from a list, or let us work it out from your website.
- We match it to every flawOver 400,000 published flaws, checked against your list.
- Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
- Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
Free plan, no card needed. Nothing to install.
1 flaw being exploited affects software Acme tracks
The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE Software contains multiple vulnerabilities that could allow an authenticated,...
- Matched to
- IOS on Acme's software list
- What to do
- Patch first, then check for signs of use
Sent to the alert recipients Acme chose. Also in the app and to Acme's webhook.
CVE-2017-6736 is a high-severity flaw in IOS from Cisco, published on 17 July 2017. It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.
It scores 8.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2017-6736 is 85 out of 100, which is Critical. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 70%.
For IOS from Cisco: 12.0 to 12.4, 15.0 to 15.6. The record lists 2 products in all, each with its versions, under "Who is affected" on this page.
Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.