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Debian LTS Advisory DLA-2753-1                [email protected]
https://www.debian.org/lts/security/                      Markus Koschany
September 02, 2021                            https://wiki.debian.org/LTS
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Package        : qemu
Version        : 1:2.8+dfsg-6+deb9u15
CVE ID         : CVE-2021-3527 CVE-2021-3592 CVE-2021-3594 CVE-2021-3595 
                 CVE-2021-3682 CVE-2021-3713
Debian Bug     : 988157 989993 989995 989996 991911 992727

Several security vulnerabilities have been found in Qemu, a fast processor
emulator.

CVE-2021-3713

  An out-of-bounds write flaw was found in the UAS (USB Attached SCSI) device
  emulation of QEMU. The device uses the guest supplied stream number
  unchecked, which can lead to out-of-bounds access to the UASDevice->data3
  and UASDevice->status3 fields. A malicious guest user could use this flaw
  to crash QEMU or potentially achieve code execution with the privileges of
  the QEMU process on the host.

CVE-2021-3682

  A flaw was found in the USB redirector device emulation of QEMU. It occurs
  when dropping packets during a bulk transfer from a SPICE client due to the
  packet queue being full. A malicious SPICE client could use this flaw to
  make QEMU call free() with faked heap chunk metadata, resulting in a crash
  of QEMU or potential code execution with the privileges of the QEMU process
  on the host.

CVE-2021-3527

  A flaw was found in the USB redirector device (usb-redir) of QEMU. Small
  USB packets are combined into a single, large transfer request, to reduce
  the overhead and improve performance. The combined size of the bulk
  transfer is used to dynamically allocate a variable length array (VLA) on
  the stack without proper validation. Since the total size is not bounded, a
  malicious guest could use this flaw to influence the array length and cause
  the QEMU process to perform an excessive allocation on the stack, resulting
  in a denial of service.

CVE-2021-3594

  An invalid pointer initialization issue was found in the SLiRP networking
  implementation of QEMU. The flaw exists in the udp_input() function and
  could occur while processing a udp packet that is smaller than the size of
  the 'udphdr' structure. This issue may lead to out-of-bounds read access or
  indirect host memory disclosure to the guest. The highest threat from this
  vulnerability is to data confidentiality.

CVE-2021-3592

  An invalid pointer initialization issue was found in the SLiRP networking
  implementation of QEMU. The flaw exists in the bootp_input() function and
  could occur while processing a udp packet that is smaller than the size of
  the 'bootp_t' structure. A malicious guest could use this flaw to leak 10
  bytes of uninitialized heap memory from the host. The highest threat from
  this vulnerability is to data confidentiality.

CVE-2021-3595

  An invalid pointer initialization issue was found in the SLiRP networking
  implementation of QEMU. The flaw exists in the tftp_input() function and
  could occur while processing a udp packet that is smaller than the size of
  the 'tftp_t' structure. This issue may lead to out-of-bounds read access or
  indirect host memory disclosure to the guest. The highest threat from this
  vulnerability is to data confidentiality.

For Debian 9 stretch, these problems have been fixed in version
1:2.8+dfsg-6+deb9u15.

We recommend that you upgrade your qemu packages.

For the detailed security status of qemu please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/qemu

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