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)
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.706 (99.4th percentile), scored .
High probability of exploitation in the next 30 days — patch promptly. 99th percentile — 99.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.706 · newest: 0.706 · change: 0.000
Affected products
- Apache HTTP Server
- Apache Software Foundation HTTP Server — versions 2.4.55
Weakness classification (CWE)
Public proof-of-concept exploits
References
- httpd.apache.org/security/vulnerabilities_24.html (vendor-advisory, Vendor Advisory)
- security.netapp.com/advisory/ntap-20231027-0011/ (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.