Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=745 We have identified the following crash due to an invalid read in Foxit PDF Reader (version 1.0.1.0925 for Linux 64-bit), when started with a specially crafted PDF file in the following way: $ DISPLAY=:1 FoxitReader /path/to/poc/file.pdf The DISPLAY=:1 environment variable is set due to the fact that we are testing the application with a virtual X server (Xvfb), but the issue should be equally reproducible with the program started with standard display settings, too. An example excerpt from the crash log is as follows: --- cut --- Program received signal SIGSEGV, Segmentation fault. 0x0000000000ab467f in CFX_WideString::operator=(CFX_WideString const&) () (gdb) where #0 0x0000000000ab467f in CFX_WideString::operator=(CFX_WideString const&) () #1 0x00000000006c53a8 in CRichTextXML::ParseXML2Text(CXML_Element*, CRichTextXML::STYLE*, CRichTextXML::STYLE*) () #2 0x00000000006c5357 in CRichTextXML::ParseXML2Text(CXML_Element*, CRichTextXML::STYLE*, CRichTextXML::STYLE*) () #3 0x00000000006c5357 in CRichTextXML::ParseXML2Text(CXML_Element*, CRichTextXML::STYLE*, CRichTextXML::STYLE*) () #4 0x00000000006c6364 in CRichTextXML::ParseXML2Text() () #5 0x00000000006c6a33 in CRichTextXML::SetXML(wchar_t const*, wchar_t const*) () #6 0x00000000006c9d49 in CFX_Edit::SetRichTextByXML(wchar_t const*, wchar_t const*, int, int) () #7 0x000000000067e995 in CPWL_Note_Contents::SetRichText(CFX_WideString const&) () #8 0x000000000067e9e5 in CPWL_NoteItem::SetRichContents(CFX_WideString const&) () #9 0x00000000005cbcc7 in CMarkup_Popup::SetNoteContents(CFX_WideString const&, CReader_PageView*) () #10 0x00000000005ca0e7 in CMarkup_Popup::InitNote(CReader_PageView*) () #11 0x00000000005ca420 in CMarkup_Popup::CreateNote(CReader_PageView*, int) () #12 0x00000000005cd578 in CMarkup_Popup::UpdateNote(CReader_PageView*, int) () #13 0x00000000005d2475 in CMarkup_AnnotHandler::OnPageVisible(CReader_PageView*, CReader_Annot*) () #14 0x00000000006e733e in CTA_AnnotHandler::OnPageVisible(CReader_PageView*, CReader_Annot*) () #15 0x0000000000640424 in CBA_PageEventHandler::OnPageVisible(CReader_PageView*) () #16 0x0000000000461d1b in CReader_AppEx::OnPageVisible (this=0x14a5120, pDocView=0x19446a0) at ../../Readerlite/ReaderLite/src/frd_appex.cpp:2901 #17 0x0000000000450bec in CReader_ViewPage::DoPageVisibleAction (this=0x1944670) at ../../Readerlite/ReaderLite/src/preview.cpp:3204 x#18 0x000000000044b980 in CPDF_TVPreview::Slot_DoPageVisibleEvent (this=0x1943180) at ../../Readerlite/ReaderLite/src/preview.cpp:1443 #19 0x000000000044e333 in CPDFViewerEventHandler::OnFinishRender (this=0x194c520) at ../../Readerlite/ReaderLite/src/preview.cpp:2386 #20 0x000000000061db28 in CPDFViewerEx::ContinueRendering() () #21 0x000000000061de17 in CPDFViewerEx::GetRenderData(int) () #22 0x000000000044b274 in CPDF_TVPreview::paintEvent (this=0x1943180) at ../../Readerlite/ReaderLite/src/preview.cpp:1305 #23 0x00007ffff74c2302 in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #24 0x00007ffff7486c8c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #25 0x00007ffff748be56 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #26 0x00007ffff6340c2d in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #27 0x00007ffff74bcbea in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #28 0x00007ffff74bd5bc in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #29 0x00007ffff74bc786 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #30 0x00007ffff74bd5bc in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #31 0x00007ffff74bd434 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #32 0x00007ffff74bc786 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #33 0x00007ffff74bd5bc in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #34 0x00007ffff74bc786 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #35 0x00007ffff74bd5bc in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #36 0x00007ffff74bd434 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () ---Type to continue, or q to quit--- from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #37 0x00007ffff74bd434 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #38 0x00007ffff74bd434 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #39 0x00007ffff74bc786 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #40 0x00007ffff74bd5bc in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #41 0x00007ffff74bd434 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #42 0x00007ffff74bc786 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #43 0x00007ffff7493233 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #44 0x00007ffff7493941 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #45 0x00007ffff74e0973 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #46 0x00007ffff7486c8c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #47 0x00007ffff748be56 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #48 0x00007ffff6340c2d in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #49 0x00007ffff6860ea6 in QGuiApplicationPrivate::processExposeEvent(QWindowSystemInterfacePrivate::ExposeEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5 #50 0x00007ffff6861995 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5 #51 0x00007ffff684a858 in QWindowSystemInterface::sendWindowSystemEvents(QFlags) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5 #52 0x00007fffecc415b0 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so #53 0x00007ffff4a79e04 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #54 0x00007ffff4a7a048 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #55 0x00007ffff4a7a0ec in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #56 0x00007ffff638d98c in QEventDispatcherGlib::processEvents(QFlags) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #57 0x00007ffff633f96b in QEventLoop::exec(QFlags) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #58 0x00007ffff63460e1 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #59 0x0000000000439e25 in main (argc=2, argv=0x7fffffffe298) at ../../Readerlite/ReaderLite/src/main.cpp:310 (gdb) x/10i $rip => 0xab467f <_ZN14CFX_WideStringaSERKS_+51>: cmpq $0x0,0x0(%r13) 0xab4684 <_ZN14CFX_WideStringaSERKS_+56>: js 0xab4692 <_ZN14CFX_WideStringaSERKS_+70> 0xab4686 <_ZN14CFX_WideStringaSERKS_+58>: test %rbp,%rbp 0xab4689 <_ZN14CFX_WideStringaSERKS_+61>: je 0xab46a3 <_ZN14CFX_WideStringaSERKS_+87> 0xab468b <_ZN14CFX_WideStringaSERKS_+63>: cmpq $0x0,0x0(%rbp) 0xab4690 <_ZN14CFX_WideStringaSERKS_+68>: jns 0xab46a3 <_ZN14CFX_WideStringaSERKS_+87> 0xab4692 <_ZN14CFX_WideStringaSERKS_+70>: mov 0x8(%rbp),%esi 0xab4695 <_ZN14CFX_WideStringaSERKS_+73>: lea 0x10(%rbp),%rdx 0xab4699 <_ZN14CFX_WideStringaSERKS_+77>: mov %rbx,%rdi 0xab469c <_ZN14CFX_WideStringaSERKS_+80>: callq 0xab45a8 <_ZN14CFX_WideString10AssignCopyEiPKw> (gdb) info reg $r13 r13 0x740000006e 498216206446 --- cut --- Attached is a proof of concept PDF file. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39942.zip