Email Security ApplianceApplication · Cisco
CVE-2020-3370
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 URL filtering of Cisco Content Security Management Appliance (SMA) could allow an unauthenticated, remote attacker to bypass URL filtering on an affected device. The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending a crafted, malicious HTTP request to an affected device. A successful exploit could allow the attacker to redirect users to malicious sites.
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 · moderate confidenceThis is an input validation vulnerability in Cisco SMA's URL filtering component. An attacker can craft malicious HTTP requests with specially crafted URLs that bypass the filtering logic, allowing redirection of users to attacker-controlled malicious websites.
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
Email Security ApplianceApplication
< 13.0.1>= 13.5.0, < 13.5.1CVSS 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.
-
Identify Cisco Email Security Appliance versionRun the command 'version' in the ESA CLI or check the appliance GUI under System Administration > Product ID/License Information to obtain the installed firmware version.Affected if The version is below 13.0.1, or is 13.5.0 through 13.5.0-xxx (any 13.5.0 release before 13.5.1).
-
Confirm URL filtering feature is activeIn the ESA web interface, navigate to Mail Policies > URL Filtering, or run 'urlfilterconfig' in the CLI to verify if URL filtering is enabled.Affected if URL filtering is enabled and the appliance version falls within the affected ranges listed in step 1.
-
Review URL filtering policies for bypass rulesIn the ESA GUI, go to Mail Policies > URL Filtering and examine the configured URL filtering rules. Look for any rules that permit redirects to external domains or contain allowlist entries that could permit unfiltered URLs.Affected if Lenient or overly permissive URL filtering rules exist that could allow redirection to arbitrary URLs.
-
Audit recent URL-related logs for suspicious redirectsRun 'grep redirect /var/log/ironportmail.log' or use the ESA Message Tracking interface to search for URLs with redirect parameters (such as 'url=' or 'redirect=') that point to non-corporate domains.Affected if Logs show HTTP requests resulting in redirects to unfamiliar or malicious-looking domains originating from the appliance's filtering engine.
Your environment is affected if the Cisco Email Security Appliance runs version 13.0.1 through 13.0.x, 13.5.0 through 13.5.0-xxx, AND URL filtering is actively used to inspect incoming messages.
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 data13.0.113.5.1
Apply the relevant Cisco security patches for this vulnerability. If immediate patching is not possible, consider implementing additional URL filtering at upstream network devices or monitoring for suspicious redirect patterns.
Fix this in Email Security Appliance
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3370 — 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-2020-3370 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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