# What is CVE-2019-1727? > CVE-2019-1727 is a medium-severity flaw (CVSS 6.7) in NX-OS from Cisco, published on 15 May 2019. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 0.5%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2019-1727 ## At a glance - **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle. - **Precursor Intelligence risk score:** 23 out of 100 (Low); action: Monitor. Kept up to date as the evidence changes. - **Severity:** Medium (CVSS 6.7 out of 10) - **Known to be exploited:** No, not on the list of flaws known to be exploited today - **Chance of use in the next 30 days:** 0.5% (latest exploit-likelihood forecast) - **Published:** 15 May 2019 - **Record last updated:** 16 October 2020 - **Main product:** NX-OS from Cisco - **Affected products:** 27 ## What is CVE-2019-1727? In plain terms An attacker has to be already on the device with an administrator account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline. ### The official description A vulnerability in the Python scripting subsystem of Cisco NX-OS Software could allow an authenticated, local attacker to escape the Python parser and issue arbitrary commands to elevate the attacker's privilege level. The vulnerability is due to insufficient sanitization of user-supplied parameters that are passed to certain Python functions in the scripting sandbox of the affected device. An attacker could exploit this vulnerability to escape the scripting sandbox and execute arbitrary commands to elevate the attacker's privilege level. To exploit this vulnerability, the attacker must have local access and be authenticated to the targeted device with administrative or Python execution privileges. These requirements could limit the possibility of a successful exploit. ### What kind of flaw is it? - CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') ### How an attack on it works - Where an attacker can be: Already on the device - How hard it is to pull off: Easy: no special conditions - Login needed first: An administrator account - Does someone have to click: No, nobody has to do anything - What an attacker gets: Can read data, change data and take it offline Severity vector: `CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H` ## Is CVE-2019-1727 being exploited? Not that we know of It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.5%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: 0.5%, 0.5%, 0.5%, 0.5%, 0.5%, 0.5%, 0.5%. ### Timeline - 15 May 2019: Published - 16 October 2020: Record last updated ### How Precursor Intelligence ranks it CVE-2019-1727 scores **23 out of 100 (Low)**, with the action "Monitor". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2019-1727? The published record lists 27 products. Versions are as published: "5.2 to before 8.1(1b)" means from 5.2 up to, but not including, 8.1(1b). - [NX-OS](https://www.precursorintelligence.com/product/cisco/nx-os) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 5.2 to before 8.1(1b), 8.0 to before 8.3(1) - [Mds 9000](https://www.precursorintelligence.com/product/cisco/mds_9000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Mds 9100](https://www.precursorintelligence.com/product/cisco/mds_9100) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Mds 9200](https://www.precursorintelligence.com/product/cisco/mds_9200) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Mds 9500](https://www.precursorintelligence.com/product/cisco/mds_9500) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Mds 9700](https://www.precursorintelligence.com/product/cisco/mds_9700) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3000](https://www.precursorintelligence.com/product/cisco/nexus_3000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3100](https://www.precursorintelligence.com/product/cisco/nexus_3100) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3100-Z](https://www.precursorintelligence.com/product/cisco/nexus_3100-z) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3100v](https://www.precursorintelligence.com/product/cisco/nexus_3100v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3200](https://www.precursorintelligence.com/product/cisco/nexus_3200) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3400](https://www.precursorintelligence.com/product/cisco/nexus_3400) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3500](https://www.precursorintelligence.com/product/cisco/nexus_3500) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3524-X](https://www.precursorintelligence.com/product/cisco/nexus_3524-x) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3524-Xl](https://www.precursorintelligence.com/product/cisco/nexus_3524-xl) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3548-X](https://www.precursorintelligence.com/product/cisco/nexus_3548-x) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3548-Xl](https://www.precursorintelligence.com/product/cisco/nexus_3548-xl) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 3600](https://www.precursorintelligence.com/product/cisco/nexus_3600) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 5500](https://www.precursorintelligence.com/product/cisco/nexus_5500) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 5600](https://www.precursorintelligence.com/product/cisco/nexus_5600) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 6000](https://www.precursorintelligence.com/product/cisco/nexus_6000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 7000](https://www.precursorintelligence.com/product/cisco/nexus_7000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 7700](https://www.precursorintelligence.com/product/cisco/nexus_7700) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 9000](https://www.precursorintelligence.com/product/cisco/nexus_9000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 9200](https://www.precursorintelligence.com/product/cisco/nexus_9200) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 9300](https://www.precursorintelligence.com/product/cisco/nexus_9300) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified - [Nexus 9500](https://www.precursorintelligence.com/product/cisco/nexus_9500) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified ## How do I fix CVE-2019-1727? 1. **Check whether you run it.** Compare 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. 2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood. ### References - [tools.cisco.com](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-nxos-pyth-escal) (Vendor advisory) - [securityfocus.com](http://www.securityfocus.com/bid/108341) (Third-party advisory, Vulnerability database) ## Questions ### What is CVE-2019-1727? CVE-2019-1727 is a medium-severity flaw in NX-OS from Cisco, published on 15 May 2019. An attacker has to be already on the device with an administrator account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline. ### How serious is CVE-2019-1727? It scores 6.7 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2019-1727 is 23 out of 100, which is Low. Its action is "Monitor". No sign of exploitation and a low forecast. Patch it in your normal update cycle. ### Is CVE-2019-1727 being exploited? It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.5%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2019-1727 affect? For NX-OS from Cisco: 5.2 to before 8.1(1b), 8.0 to before 8.3(1). The record lists 27 products in all, each with its versions, under "Who is affected" on this page. ### How do I fix CVE-2019-1727? 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. ## Does CVE-2019-1727 affect you? Precursor Intelligence keeps checking for you: - **Tell us what you run.** Pick your software from a list, or let us work it out from your website. - **We match it to every flaw.** Over 400,000 published flaws, checked against your list. - **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it. - **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact