Security readout for executives and security teams
Plain-English summary
This issue can make an ecobee3 lite thermostat running firmware 4.5.81.200 reboot during HomeKit wireless access control setup. The known impact is service disruption, not data theft or remote control. Sources do not provide a CVSS score, patch status, or evidence of exploitation.
Executive priority
Treat as a targeted IoT availability risk. Prioritize environments where thermostat disruption affects safety, operations, or customer experience. Broader emergency response is not supported by the evidence provided.
Technical view
CVE-2021-27953 is a NULL pointer dereference in the HomeKit Wireless Access Control setup process on ecobee3 lite 4.5.81.200. A crafted HTTP request can trigger denial of service and force a reboot. The bundle does not include vulnerable code paths, authentication requirements, network adjacency, or fixed versions.
Likely exposure
Exposure appears limited to ecobee3 lite devices on firmware 4.5.81.200 with reachable HomeKit setup functionality. The source bundle does not define CPEs, broader affected versions, or whether internet exposure is required.
Exploitation context
The provided sources describe denial of service via a crafted HTTP request, but do not report active exploitation. CVE-2021-27953 is not listed as KEV in the bundle.
Researcher notes
The record lacks CVSS, CWE mapping, CPEs, fixed versions, and exploitation evidence. Validate scope carefully against vendor material before expanding affected-product claims beyond ecobee3 lite 4.5.81.200.
Mitigation direction
- Check ecobee or vendor guidance for fixed firmware and update availability.
- Inventory ecobee3 lite devices and record firmware versions.
- Restrict access to IoT device management interfaces to trusted networks.
- Segment thermostats from user workstations and critical systems.
- Monitor affected devices for unexpected reboot patterns.
Validation and detection
- Confirm whether any ecobee3 lite devices run firmware 4.5.81.200.
- Review network paths that can reach thermostat setup or management services.
- Check logs or monitoring for repeated unexpected thermostat reboots.
- Verify whether vendor firmware or configuration guidance has been applied.
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.
CVE-2021-27953 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.l9group.com/advisories/remote-denial-of-service-of-ecobee3-liteCVE reference · x_refsource_MISC
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.