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Secure Firewall Threat DefenseApplication · Cisco

CVE-2021-34794

MEDIUM · 5.3 CVSS v3.1 Published 2021-10-27
Fix available
A fix is available. Upgrade to 6.4.0.13 / 6.6.5 or later.
See remediation →
62/100
Remediation priority · Elevated
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 Simple Network Management Protocol version 3 (SNMPv3) access control functionality of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to query SNMP data. This vulnerability is due to ineffective access control. An attacker could exploit this vulnerability by sending an SNMPv3 query to an affected device from a host that is not permitted by the SNMPv3 access control list. A successful exploit could allow the attacker to send an SNMP query to an affected device and retrieve information from the device. The attacker would need valid credentials to perform the SNMP query.

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 SNMPv3 access control functionality of Cisco ASA and FTD Software allows unauthenticated remote attackers from hosts not permitted by the SNMPv3 ACL to query SNMP data and retrieve sensitive device information. The access control enforcement is ineffective, allowing ACL bypass while still requiring valid SNMP credentials for the query itself.

MitigationApply the relevant Cisco security updates for ASA and FTD software. Until patched, monitor SNMP access logs for queries from unexpected source IPs and ensure SNMP ACLs are properly configured to limit exposure.

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, < 6.4.0.13>= 6.5.0, < 6.6.5>= 6.7.0, < 6.7.0.1
Adaptive Security Appliance SoftwareOperating system
Affected:>= 9.14.0, < 9.14.2.4>= 9.15.0, < 9.15.1.7
Asa 5512 X FirmwareOperating system
Affected:= 009.014\(001\)= 099.015\(001.033\)= 099.016\(001.216\)
Asa 5505 FirmwareOperating system
Affected:= 009.014\(001\)= 099.015\(001.033\)= 099.016\(001.216\)
Asa 5515 X FirmwareOperating system
Affected:= 009.014\(001\)= 099.015\(001.033\)= 099.016\(001.216\)
Asa 5525 X FirmwareOperating system
Affected:= 009.014\(001\)= 099.015\(001.033\)= 099.016\(001.216\)
Asa 5545 X FirmwareOperating system
Affected:= 009.014\(001\)= 099.015\(001.033\)= 099.016\(001.216\)
Asa 5555 X FirmwareOperating system
Affected:= 009.014\(001\)= 099.015\(001.033\)= 099.016\(001.216\)

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
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 checks

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

  1. Identify Cisco ASA or FTD software version
    Run 'show version' or check the device management interface to obtain the installed software version
    Affected if The version falls within the affected ranges: FTD 6.4.0-6.4.0.12, 6.5.0-6.6.4, 6.7.0; ASA 9.14.0-9.14.2.3, 9.15.0-9.15.1.6; or specific firmware builds listed (009.014(001), 099.015(001.033), 099.016(001.216))
  2. Verify SNMPv3 is configured
    Run 'show snmp-server' or 'show snmp-server group' to check if SNMP is enabled and which version is in use
    Affected if SNMPv3 is enabled on the device, as the vulnerability affects SNMPv3 access control specifically
  3. Review SNMP access control lists
    Run 'show snmp-server access-list' or examine the SNMP ACL configuration to see which source IP addresses are permitted
    Affected if An SNMP ACL is configured but the access control enforcement is ineffective - the device may permit SNMP queries from IPs not explicitly allowed in the ACL
  4. Check SNMP interface bindings
    Run 'show snmp-server interface' or review SNMP configuration to identify which interfaces have SNMP listening enabled
    Affected if SNMP is bound to any interface that is accessible from untrusted networks, allowing potential attackers to reach the SNMP service

You are affected if your device runs a vulnerable Cisco ASA or FTD version AND has SNMPv3 enabled, regardless of ACL configuration, because the access control bypass occurs even when valid SNMP credentials are used from non-permitted IPs.

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 6.4.0.13 / 6.6.5 / 6.7.0.1 or later
Fixed in 6.4.0.136.6.56.7.0.1
Interim mitigation

Apply the relevant Cisco security updates for ASA and FTD software. Until patched, monitor SNMP access logs for queries from unexpected source IPs and ensure SNMP ACLs are properly configured to limit exposure.

Recommended fix High confidence

Secure Firewall Threat Defense: 6.4.0.13, 6.6.5, or 6.7.0.1 | ASA Software: 9.14.2.4 or 9.15.1.7

  1. 1. Identify the currently installed Cisco ASA Software or FTD version using 'show version' command
  2. 2. Based on the installed version branch, determine the minimum fixed release: For 6.4.x branch, upgrade to 6.4.0.13 or later; For 6.5.x-6.6.x branch, upgrade to 6.6.5 or later; For 6.7.x branch, upgrade to 6.7.0.1 or later; For ASA 9.14.x branch, upgrade to 9.14.2.4 or later; For ASA 9.15.x branch, upgrade to 9.15.1.7 or later
  3. 3. Download the appropriate fixed software image from Cisco (requires valid Cisco service contract)
  4. 4. Upload the new image to the device flash storage
  5. 5. For FTD devices, use the FMC (Firepower Management Center) to upgrade the FTD software version
  6. 6. For ASA devices, use the 'install' command to perform the upgrade: 'install source <image> verbose'
  7. 7. Verify the upgrade was successful with 'show version' and confirm the new version is running
  8. 8. After upgrade, verify SNMPv3 access control is functioning correctly by testing permitted and non-permitted hosts
Caveat Software upgrades on security appliances may cause temporary service interruption; ensure maintenance window and backup configuration are in place 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
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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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-2021-34794 in production — separate from our analysis above.

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