Bash-it EUVD-2026-56927

Exploitation requires three concurrent conditions: (1) the victim must have Bash-it installed and the barbuk theme selected as their active prompt theme - other Bash-it themes are not affected; (2) the victim's working directory must contain a pyproject.toml file with escape sequences embedded in the requires-python field value; and (3) the victim must navigate into (cd into) that directory during an active terminal session, triggering prompt re-render. The attacker must have the ability to place a file in a directory the victim will visit, which requires either write access to a shared filesystem, the ability to deliver a directory via a repository or archive, or social engineering. Exploitation is blocked if the victim uses any theme other than barbuk, if no pyproject.toml is present in the current directory, or if the victim's terminal emulator ignores OSC/CSI sequences (rare in practice). The attack does not require any network connectivity, daemon or service, or elevated privileges on the victim's system.

The CVSS 4.0 score of 4.6 is calibrated appropriately for this vulnerability. The local attack vector (AV:L) is the dominant limiting factor: an attacker must be able to place a malicious pyproject.toml in a filesystem location the victim user will cd into, whether via a shared filesystem, a social engineering download, or a cloned repository. The required user interaction (UI:A) further constrains exploitation - the victim must actively navigate to the directory. Impact is bounded at Low for both confidentiality and integrity: OSC sequences can potentially exfiltrate terminal title or clipboard content on some emulators, and CSI sequences can manipulate displayed text, fake prompts, or redirect input - but cannot achieve code execution directly. There is no known active exploitation and no KEV listing. EPSS data was not provided in the source intelligence, so probabilistic exploitation likelihood cannot be quantified. The combination of file-placement prerequisite and required navigation means even a small developer team with disciplined repository hygiene is largely insulated, while environments that routinely open untrusted project directories (e.g., CI workers scanning arbitrary repos, developers triaging third-party submissions) carry meaningfully higher exposure.

An attacker creates a pyproject.toml file containing a requires-python value with embedded OSC terminal sequences - for example, a sequence that changes the terminal window title to impersonate a trusted application or writes characters to the input buffer to execute a command. The attacker delivers this file to a target directory via a shared repository, email attachment, or social engineering (e.g., 'clone and review this project'). When the victim user, running Bash-it with the barbuk theme, navigates into that directory, the injected sequences execute silently in the terminal emulator on the next prompt render without any additional user action.