Secure testing team - Dec 2011 - Bug#650880: aptitude safe-upgrade segfaults, aptitude update fails: E: Encountered a section with no Package: header

Package: aptitude
Version: 0.4.11.11-1~lenny2
Severity: grave
Tags: security
Justification: renders package unusable


Since December 2nd 2011 aptitude fails to work. 

aptitude update shows:
....
Hit http://volatile.debian.org lenny/volatile/main Packages
Hit http://volatile.debian.org lenny/volatile/contrib Packages
Hit http://volatile.debian.org lenny/volatile/non-free Packages
Reading package lists... Error!
E: Encountered a section with no Package: header
E: Problem with MergeList
/var/lib/apt/lists/security.debian.org_dists_lenny_updates_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.
E: Couldn''t rebuild package cache
E: Encountered a section with no Package: header
E: Problem with MergeList
/var/lib/apt/lists/security.debian.org_dists_lenny_updates_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

E: Encountered a section with no Package: header
E: Problem with MergeList
/var/lib/apt/lists/security.debian.org_dists_lenny_updates_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

Running aptitude upgrade then fails:

LANG=C aptitude safe-upgrade
Reading package lists... Error!
E: Encountered a section with no Package: header
E: Problem with MergeList
/var/lib/apt/lists/security.debian.org_dists_lenny_updates_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.
Reading package lists... Error!
Speicherzugriffsfehler

removing /var/lib/apt/lists/* and /var/lib/apt/lists/partial/* does not help

-- Package-specific info:
aptitude 0.4.11.11 kompiliert am Aug 10 2011 23:23:56
Compiler: g++ 4.3.2
Kompiliert gegen:
  apt-Version 4.6.0
  NCurses-Version: 5.7
  libsigc++-Version: 2.0.18
  Ept-Unterst?tzung aktiviert.

Aktuelle Bibliotheksversion:
  NCurses-Version: ncurses 5.7.20081213
  cwidget-Version: 0.5.12
  Apt-Version: 4.6.0
	libapt-pkg-libc6.7-6.so.4.6 => /usr/lib/libapt-pkg-libc6.7-6.so.4.6
(0x00002b734349d000)
	libncursesw.so.5 => /lib/libncursesw.so.5 (0x00002b734375e000)
	libsigc-2.0.so.0 => /usr/lib/libsigc-2.0.so.0 (0x00002b73439a9000)
	libcwidget.so.3 => /usr/lib/libcwidget.so.3 (0x00002b7343bae000)
	libept.so.0 => /usr/lib/libept.so.0 (0x00002b7343e82000)
	libxapian.so.15 => /usr/lib/libxapian.so.15 (0x00002b73440fb000)
	libz.so.1 => /usr/lib/libz.so.1 (0x00002b7344465000)
	libpthread.so.0 => /lib/libpthread.so.0 (0x00002b734467d000)
	libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00002b7344899000)
	libm.so.6 => /lib/libm.so.6 (0x00002b7344ba5000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00002b7344e29000)
	libc.so.6 => /lib/libc.so.6 (0x00002b7345040000)
	libutil.so.1 => /lib/libutil.so.1 (0x00002b7345393000)
	libdl.so.2 => /lib/libdl.so.2 (0x00002b7345597000)
	/lib64/ld-linux-x86-64.so.2 (0x00002b7343280000)
Terminal: xterm
$DISPLAY not set.
`which aptitude`: /usr/bin/aptitude
aptitude version information:

aptitude linkage:

-- System Information:
Debian Release: 5.0.9
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.18-6-amd64 (SMP w/1 CPU core)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages aptitude depends on:
ii  apt [libapt-pkg-libc6. 0.7.20.2+lenny2   Advanced front-end for dpkg
ii  libc6                  2.7-18lenny7      GNU C Library: Shared libraries
ii  libcwidget3            0.5.12-4          high-level terminal interface libr
ii  libept0                0.5.22            High-level library for managing De
ii  libgcc1                1:4.3.2-1.1       GCC support library
ii  libncursesw5           5.7+20081213-1    shared libraries for terminal hand
ii  libsigc++-2.0-0c2a     2.0.18-2          type-safe Signal Framework for C++
ii  libstdc++6             4.3.2-1.1         The GNU Standard C++ Library v3
ii  libxapian15            1.0.7-4           Search engine library
ii  zlib1g                 1:1.2.3.3.dfsg-12 compression library - runtime

Versions of packages aptitude recommends:
pn  aptitude-doc-en | aptitude-do <none>     (no description available)
pn  libparse-debianchangelog-perl <none>     (no description available)

Versions of packages aptitude suggests:
pn  debtags                       <none>     (no description available)
ii  tasksel                       2.78       Tool for selecting tasks for insta

-- no debconf information