dbcve.org
Secure Firewall Threat DefenseApplication · Cisco

CVE-2022-20757

HIGH · 7.5 CVSS v3.1 Published 2022-05-03
Fix available
A fix is available. Upgrade to 6.4.0.15 / 6.6.5.2 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 connection handling function in Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper traffic handling when platform limits are reached. An attacker could exploit this vulnerability by sending a high rate of UDP traffic through an affected device. A successful exploit could allow the attacker to cause all new, incoming connections to be dropped, resulting in a 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 confidence

A vulnerability in the connection handling function of Cisco Firepower Threat Defense (FTD) Software allows an unauthenticated remote attacker to cause a denial of service by sending a high rate of UDP traffic through the affected device. When platform limits are reached due to improper traffic handling, all new incoming connections are dropped.

MitigationImplement UDP traffic rate limiting on the device and monitor for unusual UDP traffic patterns; contact Cisco for available software updates/patches for FTD.

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
Secure Firewall Threat DefenseApplication
Affected:< 6.4.0.15>= 6.5.0, < 6.6.5.2>= 6.7.0, < 7.0.2= 7.1.0

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. Determine installed FTD software version
    Run the command 'show version' or 'system() show version' in the FTD CLI to retrieve the running software version.
    Affected if The installed version falls within any of these ranges: < 6.4.0.15; >= 6.5.0 and < 6.6.5.2; >= 6.7.0 and < 7.0.2; or exactly version 7.1.0.
  2. Verify UDP traffic inspection is enabled
    Check the FTD policy configuration for UDP-based traffic inspection rules using 'show service-policy' or review the access control policy settings in the FTD management interface.
    Affected if UDP traffic inspection or pass-through policies are active, allowing external UDP traffic to flow through the device.
  3. Review system logs for connection drops
    Examine system logs and connection events using 'show log' or the management center event viewer, focusing on messages related to platform limits, connection rejections, or resource exhaustion.
    Affected if Logs show a high volume of dropped new connections or platform limit warnings coinciding with elevated UDP traffic.
  4. Monitor current UDP traffic rates
    Use 'show traffic' or 'show conn' commands to inspect current connection counts and UDP traffic statistics passing through the FTD device.
    Affected if The device is processing unusually high rates of UDP traffic approaching or exceeding platform capacity limits.

A user is affected if their FTD device runs a version within the affected ranges and is processing UDP traffic that triggers platform limit exhaustion, resulting in new connection drops.

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.

dbcve · scoped
Upgrade available Upgrade to 6.4.0.15 / 6.6.5.2 / 7.0.2 or later
Fixed in 6.4.0.156.6.5.27.0.2
Interim mitigation

Implement UDP traffic rate limiting on the device and monitor for unusual UDP traffic patterns; contact Cisco for available software updates/patches for FTD.

Recommended fix Moderate confidence

6.4.0.15 (for 6.3.x), 6.6.5.2 (for 6.5.x-6.6.5.1), 7.0.2 (for 6.7.x-7.0.1), or latest 7.1.x (for 7.1.0)

  1. 1. Identify the currently installed FTD version using 'show version' or via FMC/FTD management interface
  2. 2. Determine which upgrade path applies based on current version (6.3.x -> 6.4.0.15+, 6.5.x-6.6.5.1 -> 6.6.5.2+, 6.7.x-7.0.1 -> 7.0.2+, 7.1.0 -> 7.1.1+ or latest 7.1.x)
  3. 3. Download the appropriate FTD upgrade package from Cisco.com (requires valid service contract)
  4. 4. Review Cisco FTD upgrade guides for pre-upgrade checks and compatibility requirements
  5. 5. Back up current device configuration
  6. 6. Upload upgrade package to FTD device or FMC
  7. 7. Perform upgrade via 'upgrade' command in FTD CLI or via FMC web interface
  8. 8. Verify upgrade completed successfully with 'show version'
Caveat Major version upgrades (e.g., 6.x to 7.x) may have configuration or compatibility changes; review Cisco FTD migration guides before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,790
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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-2022-20757 in production — separate from our analysis above.

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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