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             AUSCERT External Security Bulletin Redistribution

                  Apache HTTP Server 2.4 vulnerabilities
                             20 September 2021


        AusCERT Security Bulletin Summary

Product:           Apache HTTP Server
Publisher:         Apache Software Foundation
Operating System:  Windows
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service              -- Remote/Unauthenticated
                   Provide Misleading Information -- Remote/Unauthenticated
                   Access Confidential Data       -- Remote/Unauthenticated
                   Reduced Security               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-40438 CVE-2021-39275 CVE-2021-36160
                   CVE-2021-34798 CVE-2021-33193 

Reference:         ESB-2021.2985

Original Bulletin: 

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Apache HTTP Server 2.4 vulnerabilities

The initial GA release, Apache httpd 2.4.1, includes fixes for all
vulnerabilities which have been resolved in Apache httpd 2.2.22 and all older
releases. Consult the Apache httpd 2.2 vulnerabilities list for more

Fixed in Apache HTTP Server 2.4.49

moderate: Request splitting via HTTP/2 method injection and mod_proxy (

    A crafted method sent through HTTP/2 will bypass validation and be
    forwarded by mod_proxy, which can lead to request splitting or cache

    This issue affects Apache HTTP Server 2.4.17 to 2.4.48.

    Acknowledgements: Reported by James Kettle of PortSwigger

    Reported to security team 2021-05-11
    Issue public              2021-08-06
    Update 2.4.49 released    2021-09-16
    Affects                   <=2.4.48, !<2.4.17

moderate: NULL pointer dereference in httpd core (CVE-2021-34798)

    Malformed requests may cause the server to dereference a NULL pointer.

    This issue affects Apache HTTP Server 2.4.48 and earlier.

    Acknowledgements: The issue was discovered by the Apache HTTP security team

    Update 2.4.49 released 2021-09-16
    Affects                <=2.4.48

moderate: mod_proxy_uwsgi out of bound read (CVE-2021-36160)

    A carefully crafted request uri-path can cause mod_proxy_uwsgi to read
    above the allocated memory and crash (DoS).

    This issue affects Apache HTTP Server versions 2.4.30 to 2.4.48

    Acknowledgements: LI ZHI XIN from NSFocus Security Team

    Reported to security team 2021-04-26
    Update 2.4.49 release     2021-09-16
    Affects                   <=2.4.48, !<2.4.30

low: ap_escape_quotes buffer overflow (CVE-2021-39275)

    ap_escape_quotes() may write beyond the end of a buffer when given
    malicious input.

    No included modules pass untrusted data to these functions, but third-party
    / external modules may.

    This issue affects Apache HTTP Server 2.4.48 and earlier.

    Acknowledgements: ClusterFuzz

    Update 2.4.49 released 2021-09-16
    Affects                <=2.4.48

high: mod_proxy SSRF (CVE-2021-40438)

    A crafted request uri-path can cause mod_proxy to forward the request to an
    origin server choosen by the remote user.

    This issue affects Apache HTTP Server 2.4.48 and earlier.

    Acknowledgements: The issue was discovered by the Apache HTTP security team
    while analysing CVE-2021-36160

    Update 2.4.49 released 2021-09-16
    Affects                <=2.4.48

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