GHSA-48v2-6jcm-fc99 praktor: Path traversal in Telegram file uploads allows writing outside the agent workspace uploads/ directory (stored instruction injection)

• Go github.com/mtzanidakis/praktor: < 0.9.1 → fixed in 0.9.1

Impact A remote Telegram user can write files to arbitrary paths inside an agent's persistent workspace volume (`praktor-wk-`, mounted at `/workspace/agent`), escaping the documented `uploads/` directory. The attacker controls the Telegram document filename, which was concatenated into the destination path without sanitization (`internal/telegram/bot.go`, at both upload sites) and resolved with `path.Join`, which collapses `../` sequences. A filename like `../../../CLAUDE.md` resolved to the root of the agent workspace volume, outside `uploads/`. Because the agent workspace is the persistent working directory the Claude agent reads from and operates on across runs, writing outside `uploads/` lets an attacker plant or overwrite files the agent later consumes — e.g. `CLAUDE.md`, agent instruction/skill/hook files, or other config under `/workspace/agent`. This turns a file upload into a stored injection into the agent's instruction/execution surface (CWE-22 path traversal escalating to stored instruction injection). Reachability By default the bot has no user allowlist (`allow_from: []` means "allow all"), so the only precondition is that a user can message the bot. No authentication or prior privilege is required. Affected versions Through `v0.9.0` (and HEAD `3902d29`). Patched versions `v0.9.1`, containing PR #228. Workarounds Restrict `telegram.allow_from` to trusted user IDs to limit who can send uploads to the bot. Upgrading to `v0.9.1` is the recommended fix. Fix (defense in depth) • `internal/telegram/bot.go`: apply `path.Base()` to the attacker-controlled filename at both upload sites, stripping directory components and `..`. • `internal/container/manager.go`: `WriteVolumeBytes` now rejects any path that escapes `/vol` after `path.Join`, protecting future callers. Credit Reported privately by tonghuaroot, who provided a detailed root-cause analysis, a deployed end-to-end proof of concept against the real `container.Manager`, and fix verification.