CVE-2021-41524
HIGHEPSS 98th pctlDescription
While fuzzing the 2.4.49 httpd, a new null pointer dereference was detected during HTTP/2 request processing, allowing an external source to DoS the server. This requires a specially crafted request. The vulnerability was recently introduced in version 2.4.49. No exploit is known to the project.
How to fix
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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 98% of all known CVEs.
References
Related Vulnerabilities
Other CWE-476 (NULL Pointer Dereference) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-21758 | High | 7.5 | 93% | - | Fix |
| CVE-2023-21547 | High | 7.5 | 89% | - | Fix |
| CVE-2014-3470 | Medium | 4.3 | 86% | - | Fix |
| CVE-2021-44224 | High | 8.2 | 82% | - | Fix |
| CVE-2016-0742 | High | 7.5 | 82% | - | Fix |
| CVE-2009-1386 | Medium | 5.0 | 80% | - | Fix |
Common questions
How do I fix CVE-2021-41524?
Published advisories record a fix for 12 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-2021-41524 being actively exploited?
Not that we know of. CVE-2021-41524 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 25.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 98% of all scored CVEs.
How severe is CVE-2021-41524?
CVE-2021-41524 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-2021-41524 affect?
Published advisories record a fix for httpd (Amazon), httpd-debuginfo (Amazon), httpd-devel (Amazon), httpd-filesystem (Amazon), and 8 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 2026-06-17.