The HTTPS protocol does not consider the role of the TCP congestion window in providing information about content length, which makes it easier for remote attackers to obtain cleartext data by leveraging a web-browser configuration in which third-party cookies are sent, aka a "HEIST" attack.
This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.3, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts limited data confidentiality, for affected systems. Impacting 6 products from opera, from apple, from mozilla and 3 others, organizations running these solutions should prioritize assessment and patching.
First disclosed in 2016, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.
2016-09-06T10:59:00.133
2025-04-12T10:46:40.837
Deferred
CVSSv3.0: 5.3 (MEDIUM)
AV:N/AC:L/Au:N/C:P/I:N/A:N
10.0
2.9
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | opera | opera | - | Yes |
| Application | apple | safari | * | Yes |
| Application | mozilla | firefox | * | Yes |
| Application | microsoft | edge | - | Yes |
| Application | microsoft | internet_explorer | - | Yes |
| Application | chrome | - | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For opera's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.