Single-click RCE in Atril PDF link handling via ev_spawn argv injection

Repository is a small standalone Python PoC centered on a single script, CVE-2026-46529.py, plus README, license, and minimal requirements. The script is not part of a known exploit framework. Its main purpose is to generate a malicious PDF that embeds attacker-controlled URI actions, targeting claimed unsafe URI handling in Linux PDF viewers Atril, Evince, and XReader. The exploit class builds raw PDF objects manually, including a Catalog, Pages, Page, Font, content stream, annotations, and notably a /URI action plus an /OpenAction. The default payload logic constructs a file:// URI pointing to /bin/sh with -c and an attacker-supplied command, enabling local command execution if the viewer/system passes the URI unsafely to the OS. The CLI supports either a fully custom URI (-u) or a command string (-c), writes the resulting PDF to disk, and can optionally start a simple HTTP server on port 8080 to serve the generated file. README content documents example payloads including launching xterm, invoking /bin/bash, fetching a remote shell script over HTTP, and using an SMB URI. Overall, this is an operational exploit generator for malicious PDF delivery rather than a scanner or detector.

This repository is a working Linux RCE proof-of-concept for CVE-2026-46529 affecting atril, xreader, and GTK3-based evince builds. The exploit abuses argv injection in the viewers' /GoToR handling path: attacker-controlled PDF fields are interpolated into a command line without proper quoting, then reparsed into argv. By injecting a leading-space argument '--gtk-module=%f', the spawned child viewer loads an attacker-controlled shared object via GTK's module loading mechanism. Repository structure is small and purpose-built: README.md documents the vulnerability, affected versions, and usage; exploit.sh is the main operator-facing entry point that compiles the payload and builds the final artifact; evil_gtk_module.c contains the malicious shared library payload; build_polyglot.py constructs the final PDF+ELF polyglot. The Python builder reads a compiled ELF shared object, locates the GNU build-id note, overwrites that informational field with '%PDF-1.4' so the file is simultaneously accepted as both ELF and PDF, then appends a minimal PDF containing a full-page Link annotation and a /GoToR action. The /F field embeds the output basename plus '?1' to force the viewer down the spawn path, while /D contains the injected ' --gtk-module=%f' string. Glib later substitutes %f with the runtime-resolved local path of the opened file, allowing the exploit to work without knowing the victim's directory path. The payload is operational rather than just demonstrative: when the malicious module is dlopened, its constructor writes /tmp/PWNED_atril_<pid>.txt and executes a detached bash reverse shell to a configurable attacker IP and port. exploit.sh exposes those parameters via --ip and --port, compiles evil.so with gcc (or a cross-compiler), invokes build_polyglot.py, and emits a ready-to-deliver PDF. Successful exploitation requires a vulnerable viewer, Linux target matching the built architecture, preserved filename basename, user click interaction, and outbound network access for the reverse shell.