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Debian LTS Advisory DLA-2776-1                [email protected]
https://www.debian.org/lts/security/                      Sylvain Beucler
October 02, 2021                              https://wiki.debian.org/LTS
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Package        : apache2
Version        : 2.4.25-3+deb9u11
CVE ID         : CVE-2021-34798 CVE-2021-39275 CVE-2021-40438

Several vulnerabilities were discovered in the Apache HTTP server.
An attacker could send proxied requests to arbitrary servers, corrupt
memory in some setups involving third-party modules, and cause the
server to crash.


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


    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.


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

For Debian 9 stretch, these problems have been fixed in version

We recommend that you upgrade your apache2 packages.

For the detailed security status of apache2 please refer to
its security tracker page at:

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS