CVE-2021-1145Network attack vector

Authenticated file read via SFTP symlink following

Published Jan 13, 2021 · Updated Nov 12, 2024

Symlink following in SFTP in Cisco ASR 5000 Series Software before 21.19.7 allows remote authenticated users to read arbitrary files. StarOS accepts a crafted SFTP command and follows an attacker-controlled symbolic link without constraining the resolved path to the permitted file area. Valid device credentials and network access to SFTP are required; exploitation discloses readable device files without altering them or interrupting service.

CVSS severity6.5
Medium
EPSS probability1.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Symlink following in SFTP in Cisco ASR 5000 Series Software before 21.19.7 allows remote authenticated users to read arbitrary files. StarOS accepts a crafted SFTP command and follows an attacker-controlled symbolic link without constraining the resolved path to the permitted file area. Valid device credentials and network access to SFTP are required; exploitation discloses readable device files without altering them or interrupting service.

The record

CVE
CVE-2021-1145
Published
Jan 13, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco ASR 5000 Series Software
Classifications
CWE-61, CWE-59, T1005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 13, 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 vectornetwork
Required privilegesauthenticated

What is affected?

ClamAV · Cisco ASR 5000 Series Softwareversion=n/a

Published CVSS scores

6.5Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:X/RL:X/RC:X
4.0NISTAV:N/AC:L/Au:S/C:P/I:N/A:N
6.5NISTCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-61UNIX Symbolic Link (Symlink) Following
CWE-59Improper Link Resolution Before File Access ('Link Following')
T1005Data from Local System

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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