Secure Firewall Threat DefenseApplication · Cisco
CVE-2022-20940
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 TLS handler of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to gain access to sensitive information. This vulnerability is due to improper implementation of countermeasures against a Bleichenbacher attack on a device that uses SSL decryption policies. An attacker could exploit this vulnerability by sending crafted TLS messages to an affected device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device.
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 confidenceImproper implementation of Bleichenbacher attack countermeasures in the TLS handler of Cisco FTD when SSL decryption policies are enabled. An attacker can send crafted TLS messages to exploit the device as an oracle, enabling chosen-ciphertext attacks to decrypt previously captured TLS sessions.
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
>= 6.2.3, <= 6.2.3.18>= 6.3.0, <= 6.3.0.5>= 6.4.0, <= 6.4.0.14>= 6.5.0, <= 6.5.0.5>= 6.7.0, <= 6.7.0.3>= 7.0.0, <= 7.0.3= 6.6.0= 6.6.0.1= 6.6.1= 6.6.3= 6.6.4= 6.6.5CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify FTD software versionLog into the FTD device CLI and run the command 'show version' or 'show running-config | include version' to retrieve the installed Firepower Threat Defense software version.Affected if The installed version falls within any of these ranges: 6.2.3.0 through 6.2.3.18; 6.3.0.0 through 6.3.0.5; 6.4.0.0 through 6.4.0.14; 6.5.0.0 through 6.5.0.5; 6.6.0, 6.6.0.1, 6.6.1, 6.6.3, 6.6.4, 6.6.5; 6.7.0.0 through 6.7.0.3; or 7.0.0.0 through 7.0.3.
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Confirm SSL decryption policy statusAccess the FTD management interface (Firepower Management Center or FTD CLI) and navigate to the SSL decryption policy configuration. In the CLI, you can check via 'show ssl-decryption' or similar policy inspection commands.Affected if SSL decryption policies are enabled or configured on the device. The vulnerability is only exploitable when SSL decryption is active.
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Verify TLS RSA key exchange is in useReview active TLS connections or policy configurations to determine if RSA key exchange cipher suites are permitted. Check SSL/TLS inspection policy settings for allowed cipher suites.Affected if RSA-based key exchange (such as TLS_RSA_* cipher suites) is enabled or allowed in the SSL decryption policy, as this is required for the Bleichenbacher oracle condition.
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Check for exposure to untrusted networksEvaluate whether the FTD device TLS interface is directly accessible from untrusted networks. Review access control policies and interface security levels.Affected if The device accepts TLS connections from untrusted or external networks, allowing an attacker to send crafted TLS messages to the device.
You are affected only if your FTD version matches any of the listed affected versions AND SSL decryption policies are enabled on the device.
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.
From vendor dataApply the Cisco patch for CVE-2022-20940 to affected FTD versions. Until patched, evaluate risk of SSL decryption policies and consider disabling if feasible.
Fix this in Secure Firewall Threat Defense
Scoped from the published advisory
- Consultation4.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-20940 — 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-2022-20940 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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