CVE-2019-1836

CVE-2019-1836 is a high-severity vulnerability in Cisco Nx-os with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-59.

Key facts

Description

A vulnerability in the system shell for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an authenticated, local attacker to use symbolic links to overwrite system files. These system files may be sensitive and should not be overwritable by non-root users. The attacker would need valid device credentials. The vulnerability is due to incorrect symbolic link verification of directory paths when they are used in the system shell. An attacker could exploit this vulnerability by authenticating to the device and providing crafted user input to specific symbolic link CLI commands. Successful exploitation could allow the attacker to overwrite system files that should be restricted. This vulnerability has been fixed in software version 14.1(1i).

Frequently asked questions

What is CVE-2019-1836?
A vulnerability in the system shell for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an authenticated, local attacker to use symbolic links to overwrite system files. These system files may be sensitive and should not be overwritable by non-root users. The attacker would need valid device credentials. The vulnerability is due to incorrect symbolic link verification of directory paths when they are used in the system shell. An attacker could exploit this vulnerability by authenticating to the device and providing crafted user input to specific symbolic link CLI commands. Successful exploitation could allow the attacker to overwrite system files that should be restricted. This vulnerability has been fixed in software version 14.1(1i).
How severe is CVE-2019-1836?
CVE-2019-1836 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2019-1836 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-1836?
CVE-2019-1836 affects Cisco Nx-os. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-1836?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-1836 published?
CVE-2019-1836 was published on 2019-05-03 and last updated on 2026-06-17.

References

Affected products (1)

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