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Adaptive Security ApplianceApplication · Cisco

CVE-2021-34787

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 identity-based firewall (IDFW) rule processing feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass security protections. This vulnerability is due to improper handling of network requests by affected devices configured to use object group search. An attacker could exploit this vulnerability by sending a specially crafted network request to an affected device. A successful exploit could allow the attacker to bypass access control list (ACL) rules on the device, bypass security protections, and send network traffic to unauthorized hosts.

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 confidence

A vulnerability in Cisco ASA and FTD software's identity-based firewall (IDFW) rule processing allows unauthenticated remote attackers to bypass ACL rules. The issue stems from improper handling of network requests when devices are configured to use object group search, enabling specially crafted requests to circumvent security controls.

MitigationApply Cisco security updates for ASA and FTD software. If patches are unavailable, consider disabling object group search for IDFW rules or implementing additional layer of filtering until patched.

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:< 9.8.4.40
Secure Firewall Threat DefenseApplication
Affected:< 6.4.0.13>= 6.5.0, < 6.6.5>= 6.7.0, < 6.7.0.3>= 7.0.0, < 7.0.1
Adaptive Security Appliance SoftwareOperating system
Affected:>= 9.9.0, < 9.12.4.25>= 9.13.0, < 9.14.3.1>= 9.15.0, < 9.15.1.17>= 9.16.0, < 9.16.1.28
Asa 5512 X FirmwareOperating system
Affected:= 009.009= 009.012
Asa 5505 FirmwareOperating system
Affected:= 009.009= 009.012
Asa 5515 X FirmwareOperating system
Affected:= 009.009= 009.012
Asa 5525 X FirmwareOperating system
Affected:= 009.009= 009.012
Asa 5545 X FirmwareOperating system
Affected:= 009.009= 009.012

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 the ASA or FTD software version
    Run 'show version' on the device CLI to retrieve the installed software version number
    Affected if The version falls within any of the following ranges: ASA < 9.8.4.40; FTD < 6.4.0.13, >= 6.5.0 < 6.6.5, >= 6.7.0 < 6.7.0.3, >= 7.0.0 < 7.0.1; ASA >= 9.9.0 < 9.12.4.25, >= 9.13.0 < 9.14.3.1, >= 9.15.0 < 9.15.1.17, >= 9.16.0 < 9.16.1.28; or for 5512X/5505/5515X/5525X/5545X firmware versions 009.009 or
  2. Verify if identity-based firewall (IDFW) is configured
    Run 'show running-config | include identity' or check for 'identity' keyword in the access-list or object-group configurations
    Affected if IDFW rules or identity-based policies are actively configured on the device
  3. Confirm if object group search is enabled
    Run 'show running-config object-group-search' or check for 'object-group-search' in the running configuration
    Affected if Object group search is enabled globally or for IDFW policies, which is required for the bypass to be exploitable
  4. Review active IDFW access rules
    Run 'show access-list' and examine ACL entries that reference identity-based objects or user/group specifications
    Affected if IDFW-based ACL rules exist that could be bypassed by specially crafted network requests

You are affected if your device runs a vulnerable ASA or FTD version AND has IDFW rules configured with object group search enabled, allowing crafted requests to potentially bypass your ACL controls.

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 / 6.7.0.3 or later
Fixed in 6.4.0.136.6.56.7.0.3
Interim mitigation

Apply Cisco security updates for ASA and FTD software. If patches are unavailable, consider disabling object group search for IDFW rules or implementing additional layer of filtering until patched.

Recommended fix High confidence

Upgrade to Cisco ASA 9.8.4.40+ / 9.12.4.25+ / 9.14.3.1+ / 9.15.1.17+ / 9.16.1.28+ (depending on your current train) or FTD 6.4.0.13+ / 6.6.5+ / 6.7.0.3+ / 7.0.1+

  1. 1. Identify the currently installed Cisco ASA Software or FTD version using 'show version' command
  2. 2. Determine which software train (branch) your current version belongs to (e.g., 9.8.x, 9.12.x, 9.14.x, 9.15.x, 9.16.x for ASA; or 6.4.x, 6.5.x, 6.6.x, 6.7.x, 7.0.x for FTD)
  3. 3. For ASA Software: upgrade to the fixed version for your train: 9.8.4.40, 9.12.4.25, 9.14.3.1, 9.15.1.17, or 9.16.1.28 or later
  4. 4. For Secure Firewall Threat Defense: upgrade to 6.4.0.13, 6.6.5, 6.7.0.3, 7.0.1 or later depending on your current train
  5. 5. For ASA hardware appliances (5505, 5512-X, 5515-X, 5525-X, 5545-X): upgrade to firmware version 9.12(4.25) or later
  6. 6. After upgrade, verify the fix by confirming the new version is installed: show version
  7. 7. Test that IDFW rules and ACLs are functioning correctly with object group search enabled
Caveat Review Cisco ASA upgrade prerequisites and release notes for compatibility; some upgrades may require intermediate steps if crossing major version boundaries

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

Fix this in Adaptive Security Appliance Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2021-34787 in production — separate from our analysis above.

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