Several vulnerabilities were fixed in qt4-x11, the legacy version of the Qt toolkit.
Double-free or corruption in QXmlStreamReader during parsing of a specially crafted illegal XML document.
A malformed SVG image causes a segmentation fault.
A malformed GIF image causes a NULL pointer dereference in QGifHandler resulting in a segmentation fault.
Uncontrolled Resource Consumption in QTgaFile.
A malformed PPM image causes a crash.
QBmpHandler segfault on malformed BMP file.
Buffer over-read in the XBM parser.
For Debian 9 stretch, these problems have been fixed in version 4:4.8.7+dfsg-11+deb9u1.
We recommend that you upgrade your qt4-x11 packages.
For the detailed security status of qt4-x11 please refer to its security tracker page at: https://security-tracker.debian.org/tracker/qt4-x11
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