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             AUSCERT External Security Bulletin Redistribution

                               ESB-2021.3296
          Null pointer dereference in h2 fuzzing (CVE-2021-41524)
                              6 October 2021

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Apache HTTP Server
Publisher:         Apache Software Foundation
Operating System:  UNIX variants (UNIX, Linux, OSX)
                   Windows
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-41524  

Original Bulletin: 
   https://httpd.apache.org/security/vulnerabilities_24.html

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Severity: moderate

Description:

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.

Mitigation:

Disable the HTTP/2 protocol.

Credit:

Apache httpd team would like to thank LI ZHI XIN from NSFocus Security Team
for reporting this issue.

    Reported to security team  2021-09-17
    fixed by r1893655 in 2.4.x 2021-09-26
    Update 2.4.50 released     2021-10-04
    Affects                    2.4.49

Fixed in Apache HTTP Server 2.4.50

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