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CVE-2018-18764: Cesanta Mongoose: Buffer overflow

CVE-2018-18764 is rated critical with a CVSS v3.0 base score of 9.1 and affects Cesanta Mongoose. Per its scoring, it can be exploited over the network, without authentication, without any user interaction.

Vulnerability description

An exploitable arbitrary memory read vulnerability exists in the MQTT packet-parsing functionality of Cesanta Mongoose 6.13. It is a heap-based buffer over-read in a parse_mqtt getu16 call. A specially crafted MQTT SUBSCRIBE packet can cause an arbitrary out-of-bounds memory read potentially resulting in information disclosure and denial of service. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

Severity breakdown

CVSS v3.0 9.1: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Unchanged. Impact stays within the vulnerable component.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: None. No loss of integrity.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-125: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

Affected products

• Cesanta Mongoose: 6.13

References

• https://github.com/TiffanyBlue/PoCbyMyself/blob/master/mongoose6.13/mqtt/Cesanta%20Mongoose%20MQTT%20getu16%20heap%20buffer%20overflow1.md
• https://github.com/TiffanyBlue/PoCbyMyself/blob/master/mongoose6.13/mqtt/Cesanta%20Mongoose%20MQTT%20getu16%20heap%20buffer%20overflow2.md