title: Apache HTTP Server: DoS in HTTP/2 with initial windows size 0
description: An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern.
This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.
This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.
Users are recommended to upgrade to version 2.4.58, which fixes the issue.
problem types: CWE-400 Uncontrolled Resource Consumption
affected:
{
defaultStatus: unaffected
product: Apache HTTP Server
vendor: Apache Software Foundation
versions:
lessThanOrEqual: 2.4.57, status: affected, version: 2.4.55, versionType: semver
}
metrics:
other: [
content: {'text': 'low'}
type: Textual description of severity
]