What is CVE-2023-43622?

CVE-2023-43622 is a high-severity vulnerability in Apache HTTP Server, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2023-10-23.

How severe is CVE-2023-43622?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2023-43622 known to be exploited?

12 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Resource exhaustion in Apache HTTP Server

CVE-2023-43622

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.

Vulnerability class: DoS (Denial of Service)

EPSS: 0.706 (99.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Apache Http_server
Apache Software Foundation Http Server — versions 2.4.55

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

Public proof-of-concept exploits

References

security@apache.org (vendor-advisory, Vendor Advisory)
security@apache.org (Third Party Advisory)

Frequently asked questions

What is CVE-2023-43622?: CVE-2023-43622 is a high-severity vulnerability in Apache HTTP Server, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2023-10-23.
How severe is CVE-2023-43622?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2023-43622 known to be exploited?: 12 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.