CVE-2023-43622
HIGHEPSS 99th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
References
Related Vulnerabilities
Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-44487 | High | 7.5 | 100% | KEV | Fix |
| CVE-2021-44228 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2011-3192 | High | 7.8 | 99% | - | Fix |
| CVE-2019-11478 | Medium | 5.3 | 95% | - | Fix |
| CVE-2023-21547 | High | 7.5 | 89% | - | Fix |
| CVE-2024-25617 | Medium | 5.3 | 89% | - | Fix |
Common questions
How do I fix CVE-2023-43622?
Published advisories record a fix for 9 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2023-43622 being actively exploited?
Not that we know of. CVE-2023-43622 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 70.6% is the estimated probability that it will be exploited in the next 30 days. That is higher than 99% of all scored CVEs.
How severe is CVE-2023-43622?
CVE-2023-43622 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2023-43622 affect?
Published advisories record a fix for apache2 (Debian), mod_http2 (Red Hat / RHEL), mod_http2 (Rocky), mod_http2-debuginfo (Red Hat / RHEL), and 5 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-02-13.