Apache HTTP Server: Denial of Service -- Remote/Unauthenticated

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.2900
       CVE-2018-11763: mod_http2, DoS via continuous SETTINGS frames
                             26 September 2018

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

Product:           Apache HTTP Server
Publisher:         The Apache Software Foundation
Operating System:  UNIX variants (UNIX, Linux, OSX)
                   Windows
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-11763  

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

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CVE-2018-11763: mod_http2, DoS via continuous SETTINGS frames

Severity: Low

Vendor: The Apache Software Foundation

Versions Affected:
httpd 2.4.17 to 2.4.34

Description:
By sending continuous, large SETTINGS frames a client can occupy a
connection, server thread and CPU time without any connection timeout
coming to effect.
This affects only HTTP/2 connections. A possible mitigation is to
not enable the h2 protocol.

Mitigation:
All httpd users should upgrade to 2.4.35 or later.

Credit:
The issue was discovered by Gal Goldshtein of F5 Networks.

References:
https://httpd.apache.org/security/vulnerabilities_24.html

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