CVE-2021-1434

Arbitrary file overwrite via insufficient CLI parameter validation

Published Mar 24, 2021 · Updated Nov 8, 2024

Arbitrary file overwrite in the CLI of Cisco IOS XE SD-WAN Software allows local users to overwrite files on the underlying host. A specific CLI command insufficiently validates its parameters before performing a file write, allowing crafted values to target an arbitrary host file. Exploitation requires high-privileged local CLI access and SD-WAN mode, which is disabled by default; successful use can replace any host file's contents.

CVSS severity4.4
Medium
EPSS probability0.23%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file overwrite in the CLI of Cisco IOS XE SD-WAN Software allows local users to overwrite files on the underlying host. A specific CLI command insufficiently validates its parameters before performing a file write, allowing crafted values to target an arbitrary host file. Exploitation requires high-privileged local CLI access and SD-WAN mode, which is disabled by default; successful use can replace any host file's contents.

The record

CVE
CVE-2021-1434
Published
Mar 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-552, T1565.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Mar 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

ClamAV · Cisco IOS XE Softwareversion=n/a

Published CVSS scores

6.6NIST NVDAV:L/AC:L/Au:N/C:N/I:C/A:C
4.4CiscoCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N/E:X/RL:X/RC:X
6.0NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-552Files or Directories Accessible to External Parties
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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