AsyncosOperating system · Cisco
CVE-2022-20653
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 DNS-based Authentication of Named Entities (DANE) email verification component of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient error handling in DNS name resolution by the affected software. An attacker could exploit this vulnerability by sending specially formatted email messages that are processed by an affected device. A successful exploit could allow the attacker to cause the device to become unreachable from management interfaces or to process additional email messages for a period of time until the device recovers, resulting in a DoS condition. Continued attacks could cause the device to become completely unavailable, resulting in a persistent DoS condition.
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 confidenceThis vulnerability exists in the DANE (DNS-based Authentication of Named Entities) email verification component of Cisco Email Security Appliance (ESA) running AsyncOS. The issue stems from insufficient error handling during DNS name resolution. An attacker can exploit this by sending specially crafted email messages to the affected device, causing DNS resolution failures that lead to the device becoming unreachable from management interfaces or unable to process email, resulting in a denial of service condition.
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
< 13.0.3>= 13.5.0, < 13.5.4.102>= 14.0, < 14.0.2.020CVSS 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
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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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Identify device model and OSLog into the ESA CLI and run the 'version' command to confirm the device is a Cisco Email Security Appliance running AsyncOS.Affected if Device is not a Cisco ESA or is not running AsyncOS - then this CVE does not apply.
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Check AsyncOS versionIn the ESA CLI, run 'version' or 'show version' to display the AsyncOS version number.Affected if The version falls into any of these ranges: < 13.0.3, >= 13.5.0 and < 13.5.4.102, or >= 14.0 and < 14.0.2.020. Compare your version against these specific ranges.
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Verify DANE feature statusIn the ESA web interface, go to Mail Policies > Inbound DKIM/DMARC Verification, or in the CLI run 'dane' or 'dnsconfig' to check if DANE verification is enabled.Affected if DANE email verification is currently enabled - this is the required component for the vulnerability to be exploitable.
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Confirm DANE verification is in useReview mail flow logs or run 'grep DANE /var/log/maillog' (or equivalent log location) to confirm DANE verification is actively processing incoming emails.Affected if DANE verification is actively processing emails - the device is actively vulnerable when the version is in the affected range.
You are affected if your Cisco ESA runs an AsyncOS version in the affected ranges AND has DANE email verification enabled and actively processing mail.
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.
dbcve · scoped13.0.313.5.4.10214.0.2.020
Apply the Cisco security update for CVE-2022-20653 when available, or disable the DANE email verification feature if not needed, while implementing network-level rate limiting on email reception as a temporary workaround.
AsyncOS 13.0.3 or later; 13.5.4.102 or later; 14.0.2.020 or later
- 1. Log into the Cisco Email Security Appliance web interface or CLI.
- 2. Navigate to System Administration > Software Update (web) or use the 'update' command (CLI) to check current AsyncOS version.
- 3. Download the appropriate fixed AsyncOS version from Cisco (13.0.3 or later, 13.5.4.102 or later, or 14.0.2.020 or later) from tools.cisco.com.
- 4. Upload the software update file to the ESA.
- 5. Initiate the upgrade and allow the system to reboot.
- 6. After reboot, verify the new version is installed by checking System Administration > Software Version.
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Asyncos
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 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 $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-20653 — 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-2022-20653 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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- Version or environment caveats, and links to real fixes
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