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Adaptive Security ApplianceApplication · Cisco

CVE-2022-20795

HIGH · 7.5 CVSS v3.1 Published 2022-04-21
Fix available
A fix is available. Upgrade to after 9.17.1.9 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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 implementation of the Datagram TLS (DTLS) protocol in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause high CPU utilization, resulting in a denial of service (DoS) condition. This vulnerability is due to suboptimal processing that occurs when establishing a DTLS tunnel as part of an AnyConnect SSL VPN connection. An attacker could exploit this vulnerability by sending a steady stream of crafted DTLS traffic to an affected device. A successful exploit could allow the attacker to exhaust resources on the affected VPN headend device. This could cause existing DTLS tunnels to stop passing traffic and prevent new DTLS tunnels from establishing, resulting in a DoS condition. Note: When the attack traffic stops, the device recovers gracefully.

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 confidence

A vulnerability in Cisco ASA and FTD software's DTLS protocol implementation allows an unauthenticated remote attacker to cause high CPU utilization by sending crafted DTLS traffic during AnyConnect SSL VPN tunnel establishment. The suboptimal processing during DTLS handshake exhausts resources, causing existing tunnels to stop passing traffic and preventing new connections.

MitigationApply Cisco patches for CVE-2022-20795. Prior to patching, consider rate limiting DTLS traffic at network perimeter, restricting VPN access via ACLs, or implementing traffic scrubbing to mitigate the attack surface.

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
Adaptive Security ApplianceApplication
Affected:<= 9.16.3
Adaptive Security Appliance SoftwareOperating system
Affected:>= 9.17.0, <= 9.17.1.9
Secure Firewall Threat DefenseApplication
Affected:<= 7.0.1>= 7.1.0.0, <= 7.1.0.1

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Cisco ASA or FTD software version
    Run 'show version' on the device CLI or check via ASDM/FMC inventory
    Affected if The version falls within <= 9.16.3, >= 9.17.0 through <= 9.17.1.9 for ASA, or <= 7.0.1, >= 7.1.0.0 through <= 7.1.0.1 for FTD
  2. Confirm AnyConnect VPN with DTLS is enabled
    Run 'show run webvpn' or 'show run anyconnect' to check for DTLS configuration; look for 'dtls' keyword in the AnyConnect profile settings
    Affected if DTLS is enabled under AnyConnect VPN configuration, as the vulnerability exploits DTLS handshake processing during tunnel establishment
  3. Check for high CPU utilization caused by DTLS processing
    Run 'show processes cpu history' or 'show cpu usage' to look for sustained high CPU; use 'show processes cpu sorted' to identify DTLS-related processes consuming resources
    Affected if CPU utilization is unusually high with DTLS or IKE daemon processes consuming disproportionate CPU cycles
  4. Inspect VPN tunnel status and DTLS handshake activity
    Run 'show vpn-sessiondb anyconnect' and 'show dtls connection' to view active tunnels and DTLS connection states; check for incomplete or stuck DTLS handshakes
    Affected if Existing AnyConnect tunnels show no traffic passing or new connections fail during DTLS handshake establishment
  5. Review system logs for DTLS handshake failures or resource exhaustion messages
    Check 'show logging' or the device syslog for DTLS errors, such as handshake timeouts, buffer exhaustion, or process crash indicators related to DTLS
    Affected if Logs show DTLS handshake failures, excessive DTLS retry attempts, or resource-related errors correlating with the vulnerability trigger condition

The environment is affected if running a vulnerable Cisco ASA or FTD version with DTLS-enabled AnyConnect VPN and experiencing high CPU or DTLS handshake issues under load.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to a release after 9.17.1.9
Interim mitigation

Apply Cisco patches for CVE-2022-20795. Prior to patching, consider rate limiting DTLS traffic at network perimeter, restricting VPN access via ACLs, or implementing traffic scrubbing to mitigate the attack surface.

Fix this in Adaptive Security Appliance Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,120
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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-2022-20795 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