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Fencer Intel
medium 5.1

CVE-2021-1390 json

Cisco IOS XE Software Local Privilege Escalation Vulnerability

published 5y ago modified 4mo ago also EUVD-2021-6857

cvss
5.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

A vulnerability in one of the diagnostic test CLI commands of Cisco IOS XE Software could allow an authenticated, local attacker to execute arbitrary code on an affected device. To exploit this vulnerability, the attacker would need to have valid user credentials at privilege level 15. This vulnerability exists because the affected software permits modification of the run-time memory of an affected device under specific circumstances. An attacker could exploit this vulnerability by authenticating to the affected device and issuing a specific diagnostic test command at the CLI. A successful exploit could trigger a logic error in the code that was designed to restrict run-time memory modifications. The attacker could take advantage of this logic error to overwrite system memory locations and execute arbitrary code on the underlying Linux operating system (OS) of the affected device.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2y ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.1 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N
NVD 3.1 6.7 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • Cisco Cisco IOS XE Software

Classification

Weakness
  • CWE-123 Write-what-where Condition
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.