CVE-2016-7153
HTTP/2: HEIST attack allows attackers to sniff TLS encrypted HTTP/2 traffic
Severity
LowRed Hat Product Security
CVSS 3.0
Review impact separately from score.
Published · August 3, 2016
Updated · November 21, 2025
Description
The HTTP/2 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.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
Disable third-party cookies in the browser.
https://support.mozilla.org/en-US/kb/disable-third-party-cookies (Firefox) https://support.google.com/chrome/answer/95647?hl=en (Google Chrome)
CVSS / CWE
CVSS 3.0 · 3.1CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
CVSS 2.0 · 2.6AV:N/AC:H/Au:N/C:P/I:N/A:N
CWE not specified