Forerunner 235 FirmwareOperating system · Garmin

CVE-2020-27483

CRITICAL · 9.9 CVSS v3.1 Published 2020-11-16
Fix available
A fix is available. Upgrade to 8.20 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable 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
Garmin Forerunner 235 before 8.20 is affected by: Array index error. The component is: ConnectIQ TVM. The attack vector is: To exploit the vulnerability, the attacker must upload a malicious ConnectIQ application to the ConnectIQ store. The ConnectIQ program interpreter trusts the offset provided for the stack value duplication instruction, DUP. The offset is unchecked and memory prior to the start of the execution stack can be read and treated as a TVM object. A successful exploit could use the vulnerability to leak runtime information such as the heap handle or pointer for a number of TVM context variables. Some reachable values may be controlled enough to forge a TVM object on the stack, leading to possible remote code execution.

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

A detailed technical summary for this CVE is being prepared.

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
Forerunner 235 FirmwareOperating system
Affected:>= 7.90, < 8.20

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
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

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 8.20 or later
Fixed in 8.20
Recommended fix High confidence

Firmware version 8.20 or later

  1. 1. Ensure the Garmin Forerunner 235 watch is sufficiently charged before starting the update
  2. 2. Connect the watch to a computer using the included USB cable
  3. 3. Open Garmin Express or Garmin Connect application
  4. 4. Wait for the application to detect the connected device
  5. 5. Check for available firmware updates
  6. 6. If firmware version 8.20 or later is available, proceed with the update
  7. 7. Allow the update to complete fully without disconnecting the device
  8. 8. Verify the firmware has been updated by checking the device settings or Garmin Connect
Caveat Firmware updates may reset some device settings to defaults; reconfigure personal preferences after update

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

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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-2020-27483 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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