CVE-2023-43622CWE-400

Apache HTTP Server: DoS in HTTP/2 with initial windows size 0

published October 23, 2023

Patch now

High probability of exploitation

NVD has not assigned a CVSS score to this record. It sits in the 99.3th percentile for exploit probability.

CVSS
—
EPSS
69%
Percentile
99.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS
Not scored
CVSS v4.0
Not supplied
EPSS
0.68818 · 99.3th percentile
Weakness
CWE-400 · Uncontrolled Resource Consumption
Published
2023-10-23T06:50Z
EPSS history
Timeline
  • 23 OCT 06:50Z
    Apache HTTP Server: DoS in HTTP/2 with initial windows size 0
    cvelistv5