Quantum Secular Labs / Blog / Advisories

CVE-2016-9063: Mozilla Firefox: Buffer overflow

CVE-2016-9063 is rated critical with a CVSS v3.1 base score of 9.8 and affects Mozilla Firefox, along with 2 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

An integer overflow during the parsing of XML using the Expat library. This vulnerability affects Firefox < 50.

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-190: Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Affected products

  • Mozilla Firefox: before 50
  • Debian Linux: 8.0; 9.0; 10.0
  • Python: from 2.7.0 before 2.7.15; from 3.3.0 before 3.3.7; from 3.4.0 before 3.4.7; from 3.5.0 before 3.5.4; from 3.6.0 before 3.6.2

References