CVE-2026-41857: BOSH CLI Remote Code Execution Vulnerability

CVE-2026-41857 Overview

CVE-2026-41857 is a shell command injection vulnerability in the BOSH command-line interface (CLI). A compromised or malicious BOSH Director can execute arbitrary shell commands on an operator's workstation when the operator invokes bosh ssh, bosh scp, or bosh logs -f with default flags. The flaw affects BOSH CLI versions prior to 7.10.5. Exploitation requires operator interaction with a Director that returns attacker-controlled data, allowing the adversary to pivot from a controlled Director into the trusted administrative workstation used to manage Cloud Foundry deployments.

Critical Impact
An attacker controlling a BOSH Director can achieve arbitrary command execution on operator workstations, potentially compromising deployment credentials, SSH keys, and access to every environment managed from that host.

Affected Products

BOSH CLI versions prior to 7.10.5
Cloud Foundry deployments managed through vulnerable BOSH CLI versions
Operator workstations executing bosh ssh, bosh scp, or bosh logs -f

Discovery Timeline

2026-07-09 - CVE CVE-2026-41857 published to NVD
2026-07-09 - Last updated in NVD database

Technical Details for CVE-2026-41857

Vulnerability Analysis

The BOSH CLI acts as the primary administrative tool for Cloud Foundry infrastructure. Operators run commands such as bosh ssh to open interactive sessions on managed virtual machines through the BOSH Director. The Director returns connection metadata that the CLI passes to a local shell process. The CLI fails to properly sanitize this metadata before constructing shell command arguments. An attacker who controls or compromises a Director can return crafted values that break out of the intended argument context and execute arbitrary commands on the operator workstation.

The vulnerability triggers under default invocation flags, meaning operators following documented workflows are exposed without any misconfiguration on their part. The blast radius extends beyond the Director because operator workstations typically hold credentials for multiple environments, private keys, and cloud provider tokens.

Root Cause

The root cause is improper neutralization of special elements used in shell commands within the BOSH CLI. The CLI concatenates Director-supplied strings into shell invocations rather than passing them as isolated arguments to execve-style calls. Metacharacters such as backticks, $(), semicolons, and pipe characters retain their shell meaning during expansion, allowing arbitrary command execution.

Attack Vector

The attack vector is local to the operator workstation but originates from a remote or compromised Director. An attacker either compromises a legitimate Director or convinces an operator to target a malicious one. The operator then executes bosh ssh, bosh scp, or bosh logs -f. The Director responds with crafted payloads embedded in fields consumed by the CLI. The CLI expands these payloads through the local shell, executing attacker code with the operator's privileges. Refer to the Cloud Foundry Blog Analysis for detailed technical description of the injection sinks.

Detection Methods for CVE-2026-41857

Indicators of Compromise

Unexpected child processes spawned by the bosh CLI binary, particularly shells (sh, bash) executing commands unrelated to SSH or SCP transport.
Outbound network connections from operator workstations to unfamiliar hosts shortly after bosh ssh, bosh scp, or bosh logs -f execution.
Modifications to shell profile files (~/.bashrc, ~/.zshrc, ~/.ssh/authorized_keys) following BOSH CLI usage.

Detection Strategies

Monitor process ancestry on operator workstations for bosh spawning interpreters or utilities such as curl, wget, nc, or python outside expected transport binaries.
Alert on BOSH CLI executions targeting Director endpoints that are not on an approved allowlist.
Correlate BOSH command invocations with subsequent credential file access events (~/.ssh/, ~/.aws/, cloud config directories).

Monitoring Recommendations

Enable command-line auditing on operator workstations to capture full argument vectors for every bosh invocation.
Forward endpoint telemetry from administrative workstations to a centralized analytics platform for retroactive hunting across BOSH sessions.
Track BOSH CLI version inventory across all administrative hosts and flag any host running a version earlier than 7.10.5.

How to Mitigate CVE-2026-41857

Immediate Actions Required

Upgrade the BOSH CLI to version 7.10.5 or later on every operator workstation before running further bosh ssh, bosh scp, or bosh logs -f commands.
Rotate credentials, SSH keys, and cloud provider tokens accessible from workstations that recently interacted with untrusted or unverified Directors.
Audit BOSH Director instances for signs of compromise, including unauthorized configuration changes and unexpected outbound traffic.

Patch Information

Cloud Foundry released BOSH CLI version 7.10.5 which resolves the shell injection by properly quoting or passing Director-supplied values as discrete arguments rather than shell strings. Full details are documented in the Cloud Foundry Blog Analysis.

Workarounds

Restrict BOSH CLI usage to Directors under trusted administrative control until patching is complete.
Run BOSH commands from isolated, ephemeral workstations or containers that do not hold long-lived credentials.
Avoid bosh ssh, bosh scp, and bosh logs -f on unpatched CLIs; use out-of-band SSH access where operationally feasible.

bash

# Verify installed BOSH CLI version and upgrade if below 7.10.5
bosh --version
# Upgrade example (Linux)
curl -Lo /usr/local/bin/bosh https://github.com/cloudfoundry/bosh-cli/releases/download/v7.10.5/bosh-cli-7.10.5-linux-amd64
chmod +x /usr/local/bin/bosh
bosh --version