AsyncosOperating system · Cisco
CVE-2020-3368
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 · uneditedA vulnerability in the antispam protection mechanisms of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass the URL reputation filters on an affected device. The vulnerability is due to insufficient input validation of URLs. An attacker could exploit this vulnerability by crafting the URL in a particular way. A successful exploit could allow the attacker to bypass the URL reputation filters that are configured for the affected device, which could allow malicious URLs to pass through the 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 · high confidenceA vulnerability in Cisco AsyncOS Software for the Email Security Appliance allows unauthenticated remote attackers to bypass URL reputation filters due to insufficient input validation of URLs. Attackers can craft malicious URLs in specific ways to evade detection and pass through the affected device.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
AsyncosOperating system
< 13.5.0CVSS 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
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm Cisco Email Security Appliance is deployedIdentify whether Cisco ESA (Email Security Appliance) hardware or virtual appliance is present in your environment. Check inventory records or network documentation for ESA devices.Affected if You have a Cisco ESA in your environment and it runs AsyncOS software.
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Locate the AsyncOS versionAccess the ESA web interface or CLI and retrieve the current AsyncOS version. In the CLI, this is typically shown at login or via the 'version' command. In the web GUI, check the System Administration > System Setup page.Affected if You cannot determine the version or the version displayed is < 13.5.0.
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Compare installed version against affected rangeCompare the AsyncOS version you retrieved against the affected range: versions prior to 13.5.0. Note that version numbers follow AsyncOS release conventions.Affected if The installed AsyncOS version is less than 13.5.0 (for example, 13.0.0, 13.4.1, 12.x, etc.).
If your Cisco ESA runs AsyncOS versions prior to 13.5.0, your environment is affected by this URL reputation filter bypass vulnerability.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor data13.5.0
Apply the relevant Cisco security update/patch for AsyncOS Software. In the interim, implement additional email security controls such as content filtering or secondary URL scanning to catch threats that bypass the ESA reputation filters.
Fix this in Asyncos
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3368 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-3368 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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