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Web Security ApplianceApplication · Cisco

CVE-2021-1359

HIGH · 8.8 CVSS v3.1 Developing Published 2021-07-08
Fix available
A fix is available. Upgrade to 12.0.3-005 / 12.5.2 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

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 configuration management of Cisco AsyncOS for Cisco Web Security Appliance (WSA) could allow an authenticated, remote attacker to perform command injection and elevate privileges to root. This vulnerability is due to insufficient validation of user-supplied XML input for the web interface. An attacker could exploit this vulnerability by uploading crafted XML configuration files that contain scripting code to a vulnerable device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system and elevate privileges to root. An attacker would need a valid user account with the rights to upload configuration files to exploit this vulnerability.

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 · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-02.

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
Web Security ApplianceApplication
Affected:= 11.8.0-429= 11.8.0-453
AsyncosOperating system
Affected:>= 11.8.0, < 12.0.3-005>= 12.5.0, < 12.5.2

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
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/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 12.0.3-005 / 12.5.2 or later
Fixed in 12.0.3-00512.5.2
Recommended fix High confidence

AsyncOS 12.0.3-005 (or later 12.0.x) for 11.8.x/12.0.x systems; AsyncOS 12.5.2 (or later 12.5.x) for 12.5.x systems

  1. Identify the currently running AsyncOS version on the WSA device via the web interface (System Administration > System Status) or CLI (show version command)
  2. Determine which upgrade path applies based on current version: for 11.8.x branch upgrade to 12.0.3-005 or later, for 12.0.x branch upgrade to 12.0.3-005 or later, for 12.5.x branch upgrade to 12.5.2 or later
  3. Download the appropriate AsyncOS upgrade image from Cisco (requires valid support contract)
  4. Schedule a maintenance window as upgrades require downtime
  5. Back up the current WSA configuration via the web interface (System Administration > Configuration File > Backup)
  6. Upload the new AsyncOS image via the web interface (System Administration > Upgrade > Upload Upgrade File) or CLI (upgrade command)
  7. Follow the on-screen prompts to complete the upgrade
  8. After reboot, verify the new version is running and confirm all services are operational
Caveat Standard AsyncOS upgrade—may require brief downtime; review release notes for any configuration changes or migration requirements

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-2021-1359 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
  • No spam, self-promotion, credentials, or personal data