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Sd WanApplication · Cisco

CVE-2021-1612

HIGH · 7.1 CVSS v3.1 Published 2021-09-23
Fix available
A fix is available. Upgrade to 17.3.4 or later.
See remediation →
73/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the Cisco IOS XE SD-WAN Software CLI could allow an authenticated, local attacker to overwrite arbitrary files on the local system. This vulnerability is due to improper access controls on files within the local file system. An attacker could exploit this vulnerability by placing a symbolic link in a specific location on the local file system. A successful exploit could allow the attacker to overwrite arbitrary files on an affected device.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Sd WanApplication
Affected:< 17.3.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 17.3.4 or later
Fixed in 17.3.4
Vendor patch tools.cisco.com →
Recommended fix Moderate confidence

Cisco IOS XE SD-WAN Software release 17.3.4 or later

  1. Verify the current IOS XE SD-WAN software version using the 'show version' command
  2. Download Cisco IOS XE SD-WAN Software release 17.3.4 or later from the Cisco software download center
  3. Back up the current configuration using the 'copy running-config tftp:' command or other backup method
  4. Upload the new software image to the device's flash storage using 'copy tftp://<server>/<image> flash:'
  5. Configure the device to boot from the new image using 'boot system flash:<new_image_name>'
  6. Reload the device using the 'reload' command
  7. After reboot, verify the new version is running with 'show version'
  8. Verify the symlink vulnerability is addressed by confirming the device is running version 17.3.4 or later
Caveat Review Cisco release notes for 17.3.4 for any configuration changes or feature modifications that may affect your deployment

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-1612 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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