CVE-2021-1278

Root-owned file corruption via unchecked symlink creation

Published Jan 20, 2021 · Updated Nov 12, 2024

Improper link resolution in Cisco SD-WAN allows local users with valid credentials to overwrite root-owned files through crafted symlinks. The symlink creation functionality accepts an attacker-chosen target path without validation, allowing later writes to corrupt the linked root-owned file. Local authenticated access and user interaction are required; corruption of a critical system file can interrupt service.

CVSS severity6.7
Medium
EPSS probability1.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper link resolution in Cisco SD-WAN allows local users with valid credentials to overwrite root-owned files through crafted symlinks. The symlink creation functionality accepts an attacker-chosen target path without validation, allowing later writes to corrupt the linked root-owned file. Local authenticated access and user interaction are required; corruption of a critical system file can interrupt service.

The record

CVE
CVE-2021-1278
Published
Jan 20, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco SD-WAN
Classifications
CWE-59, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 12, 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 privilegesauthenticated

What is affected?

ClamAV · Cisco SD-WANversion=n/a

Published CVSS scores

6.7CiscoCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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