CVE-2021-21969
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of...
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. The HandleIncomingSeaCloudMessage function uses at [4] the json_object_get_string to populate the p_payload global variable. The p_payload is only 0x100 bytes long, and the total MQTT message could be up to 0x201 bytes. Because the function json_object_get_string will fill str based on the length of the json’s value and not the actual str size, this would result in a possible out-of-bounds write.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. The HandleIncomingSeaCloudMessage function uses at [4] the json_object_get_string to populate the p_payload global variable. The p_payload is only 0x100 bytes long, and the total MQTT message could be up to 0x201 bytes. Because the function json_object_get_string will fill str based on the length of the json’s value and not the actual str size, this would result in a possible out-of-bounds write.
- Record
CVE-2021-21969- CVSS 3.0
- 3.7 Low
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-120
- Updated
- 2026-11-02
EUVDEUVD-2021-9140
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. The HandleIncomingSeaCloudMessage function uses at [4] the json_object_get_string to populate the p_payload global variable. The p_payload is only 0x100 bytes long, and the total MQTT message could be up to 0x201 bytes. Because the function json_object_get_string will fill str based on the length of the json’s value and not the actual str size, this would result in a possible out-of-bounds write.
- Record
EUVD-2021-9140- CVSS 3.0
- 3.7 Low
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-wjf2-5mh5-257q
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of...
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. The HandleIncomingSeaCloudMessage function uses at [4] the json_object_get_string to populate the p_payload global variable. The p_payload is only 0x100 bytes long, and the total MQTT message could be up to 0x201 bytes. Because the function json_object_get_string will fill str based on the length of the json’s value and not the actual str size, this would result in a possible out-of-bounds write.
- Record
GHSA-wjf2-5mh5-257q- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-787
- Updated
- 2026-11-02
NVD
An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. The HandleIncomingSeaCloudMessage function uses at [4] the json_object_get_string to populate the p_payload global variable. The p_payload is only 0x100 bytes long, and the total MQTT message could be up to 0x201 bytes. Because the function json_object_get_string will fill str based on the length of the json’s value and not the actual str size, this would result in a possible out-of-bounds write.
- Record
CVE-2021-21969- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.0
- 3.7 Low
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS 2.0
- 6.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-120, CWE-787
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21969 is a low vulnerability (CVSS 3.7) in Sealevel Seaconnect 370w Firmware, published February 4, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.89%, the 59th percentile. No source names a fixed version.