Xpdf is a

free and open-source Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source ...

PDF viewer for operating systems supported by the Qt toolkit. Versions prior to 4.00 were written for the

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting ...

and

Motif Motif may refer to: General concepts * Motif (chess composition), an element of a move in the consideration of its purpose * Motif (folkloristics), a recurring element that creates recognizable patterns in folklore and folk-art traditions * Moti ...

Functions

Xpdf runs on nearly any

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

. Binaries are also available for

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

. Xpdf can decode LZW and read encrypted PDFs. The official version obeys the DRM restrictions of PDF files, which can prevent copying, printing, or converting some PDF files. There are patches that make Xpdf ignore these DRM restrictions, and these restrictions are patched out by the

Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of De ...

distribution. Xpdf includes several programs that don't need an X Window System, including some that extract images from PDF files or convert PDF to

PostScript PostScript (PS) is a page description language in the electronic publishing and desktop publishing realm. It is a dynamically typed, concatenative programming language. It was created at Adobe Systems by John Warnock, Charles Geschke, ...

or text. These programs run on DOS, Windows,

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

and

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

. Xpdf is also used as a back-end for other PDF readers frontends such as KPDF and GPDF, and its engine, without the X11 display components, is used for PDF viewers including BePDF on

BeOS BeOS is an operating system for personal computers first developed by Be Inc. in 1990. It was first written to run on BeBox hardware. BeOS was positioned as a multimedia platform that could be used by a substantial population of desktop users a ...

, '!PDF' on

RISC OS RISC OS is a computer operating system originally designed by Acorn Computers Ltd in Cambridge, England. First released in 1987, it was designed to run on the ARM chipset, which Acorn had designed concurrently for use in its new line of Archi ...

, on PalmPDF on

Palm OS Palm OS (also known as Garnet OS) was a mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. It is provi ...

and on Windows Mobile. Two versions exist for AmigaOS. Xpdf needs a limited version of an X11 engine called Cygnix on the host system.

AmigaOS 4 AmigaOS 4 (abbreviated as OS4 or AOS4) is a line of Amiga operating systems which runs on PowerPC microprocessors. It is mainly based on AmigaOS 3.1 source code developed by Commodore International, Commodore, and partially on version 3.9 develop ...

included AmiPDF, a PDF viewer based on 3.01 version of the Xpdf. However both Apdf and AmiPDF are native and need no X11.

xpdf-utils

The associated package "xpdf-utils" or "poppler-utils" contains tools such as pdftotext and pdfimages.

Exploit

A vulnerability in the Xpdf implementation of the

JBIG2 JBIG2 is an image compression standard for bi-level images, developed by the Joint Bi-level Image Experts Group. It is suitable for both lossless and lossy compression. According to a press release from the Group, in its lossless mode JBIG2 typic ...

file format, re-used in Apple's iOS phone operating software, was used by the

Pegasus spyware Pegasus is spyware developed by the Israeli cyber-arms company NSO Group that can be covertly installed on mobile phones (and other devices) running most versions of iOS and Android. Pegasus is able to exploit iOS versions up to 14.7, through ...

to implement a

zero-click attack An exploit (from the English verb ''to exploit'', meaning "to use something to one’s own advantage") is a piece of software, a chunk of data, or a sequence of commands that takes advantage of a bug or vulnerability to cause unintended or unanti ...

on iPhones by constructing an emulated

computer architecture In computer engineering, computer architecture is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a more detailed level, the ...

inside a JBIG2 stream. Apple fixed this "

FORCEDENTRY FORCEDENTRY, also capitalized as ForcedEntry, is a security exploit allegedly developed by NSO Group to deploy their Pegasus spyware. It enables the "Zero-click attack, zero-click" exploit that is prevalent in iOS 13 and below, but also compromis ...

" vulnerability in iOS 14.8 in September 2021.

Notes and references

Sources

External links