{"id":"PYSEC-2026-1244","summary":"ChatterBot Vulnerable to Denial of Service via Database Connection Pool Exhaustion","details":"### Summary\nChatterBot versions up to 1.2.10 are vulnerable to a denial-of-service condition caused by improper database session and connection pool management. Concurrent invocations of the get_response() method can exhaust the underlying SQLAlchemy connection pool, resulting in persistent service unavailability and requiring a manual restart to recover.\n\n### Details\nChatterBot relies on SQLAlchemy for database access and uses a connection pool with default limits. The get_response() method does not enforce concurrency limits, rate limiting, or explicit session lifecycle controls.\n\nWhen multiple threads concurrently invoke get_response(), database connections are rapidly consumed and not released in a timely manner. This leads to exhaustion of the SQLAlchemy QueuePool, causing subsequent requests to block and eventually fail with a TimeoutError.\n\nThis issue can be triggered without authentication in deployments where ChatterBot is exposed as a chatbot service, making it exploitable by remote attackers to cause denial of service.\n\nPoC Video: \nhttps://github.com/user-attachments/assets/4ee845c4-b847-4854-84ec-4b2fb2f7090f\n\n### PoC\n1. Install ChatterBot version 1.2.10.\n2. Use the default database configuration (SQLite / SQLAlchemy).\n3. Run the following Python script to invoke concurrent requests:\n\nfrom chatterbot import ChatBot\nimport threading\n\nbot = ChatBot(\"dos-test\")\n\ndef attack():\n    bot.get_response(\"hello\")\n\nthreads = []\nfor _ in range(30):\n    t = threading.Thread(target=attack)\n    t.start()\n    threads.append(t)\n\nfor t in threads:\n    t.join()\n\n4. Observe that the application becomes unresponsive and raises SQLAlchemy TimeoutError exceptions indicating exhaustion of the connection pool.\n\n### Impact\nThis vulnerability allows an attacker to trigger a denial-of-service condition by exhausting the database connection pool. Once triggered, the chatbot becomes unresponsive to legitimate users and requires a manual restart to restore functionality.\n\nAll deployments of ChatterBot version 1.2.10 or earlier that allow concurrent access to the get_response() method are impacted.","aliases":["CVE-2026-23842","GHSA-v4w8-49pv-mf72"],"modified":"2026-07-07T17:47:27.106045442Z","published":"2026-07-07T16:03:19.183779Z","references":[{"type":"WEB","url":"https://github.com/gunthercox/ChatterBot/security/advisories/GHSA-v4w8-49pv-mf72"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23842"},{"type":"WEB","url":"https://github.com/gunthercox/ChatterBot/pull/2432"},{"type":"WEB","url":"https://github.com/gunthercox/ChatterBot/commit/de89fe648139f8eeacc998ad4524fab291a378cf"},{"type":"PACKAGE","url":"https://github.com/gunthercox/ChatterBot"},{"type":"WEB","url":"https://github.com/gunthercox/ChatterBot/releases/tag/1.2.11"},{"type":"WEB","url":"https://github.com/user-attachments/assets/4ee845c4-b847-4854-84ec-4b2fb2f7090f"},{"type":"PACKAGE","url":"https://pypi.org/project/chatterbot"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-v4w8-49pv-mf72"}],"affected":[{"package":{"name":"chatterbot","ecosystem":"PyPI","purl":"pkg:pypi/chatterbot"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.11"}]}],"versions":["0.0.0","0.0.1","0.0.2","0.0.3","0.0.4","0.0.5","0.1.0","0.1.1","0.1.2","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","0.2.5","0.2.6","0.2.7","0.2.8","0.2.9","0.3.0","0.3.1","0.3.2","0.3.3","0.3.4","0.3.5","0.3.6","0.3.7","0.4.0","0.4.1","0.4.10","0.4.11","0.4.12","0.4.13","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.4.7","0.4.8","0.4.9","0.5.0","0.5.1","0.5.2","0.5.3","0.5.4","0.5.5","0.6.0","0.6.1","0.6.2","0.6.3","0.7.0","0.7.1","0.7.2","0.7.3","0.7.4","0.7.5","0.7.6","0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.8.5","0.8.6","0.8.7","1.0.0","1.0.0a1","1.0.0a2","1.0.0a3","1.0.0a4","1.0.1","1.0.2","1.0.3","1.0.4","1.0.5","1.0.7","1.0.8","1.1.0","1.1.0a7","1.2.0","1.2.1","1.2.10","1.2.2","1.2.3","1.2.4","1.2.5","1.2.6","1.2.7","1.2.8","1.2.9"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/chatterbot/PYSEC-2026-1244.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}