Security readout for executives and security teams
Plain-English summary
Johnson Controls KT-1 door controllers can accept captured network traffic again, which may let an unauthenticated network attacker influence physical access-control behavior. For executives, this is a high-risk issue because door-control systems can affect facility security, not just IT systems.
Executive priority
Prioritize this for facilities using KT-1 because the impact can cross from cyber risk into physical security. The urgency is high when controllers are network-reachable beyond tightly controlled security infrastructure.
Technical view
CVE-2021-27662 is a CWE-294 capture-replay weakness in Johnson Controls KT-1. All versions up to and including 3.01 are affected. The CVSS 3.1 score is 8.6, with network attack vector, low complexity, no privileges, no user interaction, and high integrity impact.
Likely exposure
Exposure is most likely where KT-1 controllers at version 3.01 or earlier are reachable from untrusted, flat, or poorly segmented networks. The provided sources do not identify other affected Johnson Controls products.
Exploitation context
The CVE states replay or man-in-the-middle attacks are possible by recording and replaying TCP packets. The source bundle does not show CISA KEV listing, active exploitation, public exploit code, or real-world incidents.
Researcher notes
The provided record gives affected product, version range, weakness class, and CVSS details, but not a specific fixed build or mitigation text. Avoid assuming patch status. Validate exposure through asset inventory, firmware review, and network reachability analysis.
Mitigation direction
- Inventory KT-1 controllers and record firmware versions.
- Treat versions up to and including 3.01 as affected.
- Check Johnson Controls security advisories for current remediation guidance.
- Restrict KT-1 network access to trusted management systems only.
- Review access-control monitoring for unexpected door or controller activity.
- Engage the vendor if no fixed version is documented internally.
Validation and detection
- Confirm whether KT-1 devices exist in the access-control environment.
- Compare observed firmware versions against the affected range.
- Review network paths that can reach KT-1 controller TCP services.
- Check logs for unexplained access-control state changes or commands.
- Document compensating controls if vendor remediation is unavailable.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-294: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-27662 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L3.94.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://www.johnsoncontrols.com/cyber-solutions/security-advisoriesCVE reference · x_refsource_CONFIRM
- ICS-CERT AdvisoryCVE reference · third-party-advisory, x_refsource_CERT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Authentication Bypass by Capture-replay
Authentication Bypass by Capture-replay represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.