CVE-2026-35667

Description

> Fixed in OpenClaw 2026.3.24, the current shipping release. ### Advisory Details **Title**: Incomplete Fix for CVE-2026-27486: Unvalidated SIGKILL in `!stop` Chat Command via `shell-utils.ts` **Description**: ### Summary The `!stop` (and `/bash stop`) chat command kills background bash processes using `SIGKILL` directly, without first sending `SIGTERM` to allow graceful shutdown. This is because `bash-command.ts` imports `killProcessTree()` from `src/agents/shell-utils.ts`, which still contains the pre-CVE-2026-27486 aggressive kill logic, rather than from the patched `src/process/kill-tree.ts`. ### Details CVE-2026-27486 fixed unsafe process termination by introducing a graceful shutdown sequence in `src/process/kill-tree.ts` — sending `SIGTERM` first, waiting a configurable grace period (default 3 seconds), then escalating to `SIGKILL` only if the process is still alive. However, an identical copy of the **unpatched** `killProcessTree` function remains in `src/agents/shell-utils.ts` (lines 170–192). This function sends `SIGKILL` immediately with no `SIGTERM`: ```typescript // src/agents/shell-utils.ts:170-192 export function killProcessTree(pid: number): void { // ... Windows handling ... try { process.kill(-pid, "SIGKILL"); // Immediate hard kill, no SIGTERM } catch { try { process.kill(pid, "SIGKILL"); } catch { // process already dead } } } ``` The `!stop` chat command handler in `src/auto-reply/reply/bash-command.ts` imports and calls this vulnerable version at line 302: ```typescript // src/auto-reply/reply/bash-command.ts:5 import { killProcessTree } from "../../agents/shell-utils.js"; // src/auto-reply/reply/bash-command.ts:300-304 const pid = running.pid ?? running.child?.pid; if (pid) { killProcessTree(pid); // Calls the UNPATCHED version } markExited(running, null, "SIGKILL", "failed"); ``` Compare this to the patched version in `src/process/kill-tree.ts`: ```typescript // src/process/kill-tree.ts:46-78 function killProcessTreeUnix(pid: number, graceMs: number): void { // Step 1: Try graceful SIGTERM to process group try { process.kill(-pid, "SIGTERM"); } catch { /* ... */ } // Step 2: Wait grace period, then SIGKILL if still alive setTimeout(() => { if (isProcessAlive(-pid)) { try { process.kill(-pid, "SIGKILL"); } catch { /* ... */ } } }, graceMs).unref(); } ``` ### PoC This PoC demonstrates the difference between the vulnerable and patched code paths inside a running OpenClaw Gateway container. **Setup:** ```bash # Build and start the gateway container cd CVE-2026-27486-variant-exp/ docker compose up -d sleep 5 ``` **Exploit (vulnerable `killProcessTree` from `shell-utils.ts`):** The following script is injected into the container and executed. It starts a bash process that traps `SIGTERM` for graceful shutdown, then kills it using the same code path as `!stop`: ```javascript // exploit_sigkill.cjs — replicates src/agents/shell-utils.ts:183-190 const { spawn } = require('child_process'); const fs = require('fs'); try { fs.unlinkSync('/tmp/graceful_shutdown.txt'); } catch {} const child = spawn('/bin/bash', ['-c', 'trap \'echo GRACEFUL_SHUTDOWN > /tmp/graceful_shutdown.txt; exit 0\' SIGTERM; while true; do sleep 1; done' ], { detached: true, stdio: 'ignore' }); child.unref(); setTimeout(() => { // VULNERABLE: same as shell-utils.ts — SIGKILL only try { process.kill(-child.pid, 'SIGKILL'); } catch { try { process.kill(child.pid, 'SIGKILL'); } catch {} } setTimeout(() => { if (fs.existsSync('/tmp/graceful_shutdown.txt')) { console.log('[BLOCKED] SIGTERM was received.'); process.exit(1); } else { console.log('[EXPLOITED] SIGKILL sent directly — SIGTERM never delivered.'); process.exit(0); } }, 2000); }, 1000); ``` **Run:** ```bash python3 poc_exploit.py ``` ### Log of Evidence **Exploit output (SIGKILL only, no graceful shutdown):** ``` [*] Running exploit (vulnerable killProcessTree from shell-utils.ts)... [*] Victim PID: 78 [*] Calling vulnerable killProcessTree (SIGKILL only, no SIGTERM)... [EXPLOITED] SIGKILL sent directly — SIGTERM never delivered. [EXPLOITED] Graceful shutdown handler was NEVER invoked. [SUCCESS] CVE-2026-27486 variant confirmed: killProcessTree() in shell-utils.ts sends immediate SIGKILL, bypassing the graceful shutdown fix in process/kill-tree.ts. ``` **Control output (SIGTERM first, graceful shutdown works):** ``` [*] Running control (patched killProcessTree from process/kill-tree.ts)... [*] Victim PID: 93 [*] Calling patched killProcessTree (SIGTERM first, then SIGKILL after grace)... [NORMAL] SIGTERM received — graceful shutdown completed. Flag: GRACEFUL_SHUTDOWN [NORMAL] Control confirmed: patched killProcessTree sends SIGTERM first, allowing graceful shutdown before escalating to SIGKILL. ``` ### Impact When `!stop` is used, background processes are killed instantly via `SIGKILL` with no chance to perform cleanup. This can result in: - **Data corruption**: processes writing to files or databases are interrupted mid-write - **Resource leaks**: temporary files, lock files, and network connections are not properly released - **Security-sensitive cleanup skipped**: operations like erasing in-memory secrets or completing audit logs are bypassed This is the same class of impact that CVE-2026-27486 was filed for — the fix simply missed the `shell-utils.ts` copy of the function. ### Affected products - **Ecosystem**: npm - **Package name**: openclaw - **Affected versions**: <= 2026.3.14 - **Patched versions**: <None> ### Severity - **Severity**: Medium - **Vector string**: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H ### Weaknesses - **CWE**: CWE-404: Improper Resource Shutdown or Release ### Occurrences | Permalink | Description | | :--- | :--- | | [https://github.com/moltbot/moltbot/blob/f2849c2417/src/agents/shell-utils.ts#L170-L192](https://github.com/moltbot/moltbot/blob/f2849c2417/src/agents/shell-utils.ts#L170-L192) | The vulnerable `killProcessTree` function that sends immediate `SIGKILL` without `SIGTERM`. | | [https://github.com/moltbot/moltbot/blob/f2849c2417/src/auto-reply/reply/bash-command.ts#L5](https://github.com/moltbot/moltbot/blob/f2849c2417/src/auto-reply/reply/bash-command.ts#L5) | Import statement pulling the vulnerable `killProcessTree` from `shell-utils.ts` instead of the patched `kill-tree.ts`. | | [https://github.com/moltbot/moltbot/blob/f2849c2417/src/auto-reply/reply/bash-command.ts#L300-L304](https://github.com/moltbot/moltbot/blob/f2849c2417/src/auto-reply/reply/bash-command.ts#L300-L304) | The `!stop` handler calling the vulnerable `killProcessTree(pid)`. | | [https://github.com/moltbot/moltbot/blob/f2849c2417/src/process/kill-tree.ts#L46-L78](https://github.com/moltbot/moltbot/blob/f2849c2417/src/process/kill-tree.ts#L46-L78) | The **patched** `killProcessTreeUnix` with graceful `SIGTERM` → grace period → `SIGKILL` sequence (for reference). |