Bug#1021771: apache2: Accessing to type-map without .var suffix results 500 and apache2 exits

[Shintaro Sakahara <skhrshin@flokart.world>]

Package: apache2
Version: 2.4.54-1~deb11u1
Severity: important

Dear Maintainer,

I recently upgraded my server from Debian 10 to 11 and encountered a problem
where apache2 responded 500 Internal Server Error and then the process exited
when a URL to a type-map, which referenced CGI script as actual content,
without ".var" suffix was getting accessed.

I created a small example using Docker and put on GitHub so that everyone could
easily reproduce this problem.

https://github.com/skhrshin/apache2-crash-example

* Steps to reproduce *

1. Clone the repo into somewhere
2. Run `docker-compose build`
3. Run `docker-compose up`
4. Access to http://localhost:8081/board.cgi with your web browser

* Expected behavior *

A string "OK" is displayed.

* Actual behavior *

Your web browser gets 500 Internal Server Error.
Also, in a few seconds, the apache2 process is terminated.

I'm not sure if the problem is caused solely by apache2 package or by some
other dependencies like apache2-suexec-pristine or libapache2-mpm-itk, but
I don't know how to find it out. So I asked about this issue to Debian-user ML
if there's something I can do, but I could get no answer, so now I'm reporting
it here. Please tell me if something is insufficient and there's a way to
investigate it more.


-- Package-specific info:

-- System Information:
Debian Release: 11.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-18-amd64 (SMP w/4 CPU threads)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages apache2 depends on:
ii  apache2-bin          2.4.54-1~deb11u1
ii  apache2-data         2.4.54-1~deb11u1
ii  apache2-utils        2.4.54-1~deb11u1
ii  dpkg                 1.20.12
ii  init-system-helpers  1.60
ii  lsb-base             11.1.0
ii  mime-support         3.66
ii  perl                 5.32.1-4+deb11u2
ii  procps               2:3.3.17-5

Versions of packages apache2 recommends:
ii  ssl-cert  1.1.0+nmu1

Versions of packages apache2 suggests:
pn  apache2-doc              <none>
ii  apache2-suexec-pristine  2.4.54-1~deb11u1
ii  lynx [www-browser]       2.9.0dev.6-3~deb11u1

Versions of packages apache2-bin depends on:
ii  libapr1                  1.7.0-6+deb11u1
ii  libaprutil1              1.6.1-5
ii  libaprutil1-dbd-sqlite3  1.6.1-5
ii  libaprutil1-ldap         1.6.1-5
ii  libbrotli1               1.0.9-2+b2
ii  libc6                    2.31-13+deb11u4
ii  libcrypt1                1:4.4.18-4
ii  libcurl4                 7.74.0-1.3+deb11u3
ii  libjansson4              2.13.1-1.1
ii  libldap-2.4-2            2.4.57+dfsg-3+deb11u1
ii  liblua5.3-0              5.3.3-1.1+b1
ii  libnghttp2-14            1.43.0-1
ii  libpcre3                 2:8.39-13
ii  libssl1.1                1.1.1n-0+deb11u3
ii  libxml2                  2.9.10+dfsg-6.7+deb11u2
ii  perl                     5.32.1-4+deb11u2
ii  zlib1g                   1:1.2.11.dfsg-2+deb11u2

Versions of packages apache2-bin suggests:
pn  apache2-doc              <none>
ii  apache2-suexec-pristine  2.4.54-1~deb11u1
ii  lynx [www-browser]       2.9.0dev.6-3~deb11u1

Versions of packages apache2 is related to:
ii  apache2      2.4.54-1~deb11u1
ii  apache2-bin  2.4.54-1~deb11u1

-- Configuration Files:
/etc/apache2/conf-available/other-vhosts-access-log.conf changed [not included]
/etc/apache2/ports.conf changed [not included]

-- no debconf information