/proc/self/environ file is used to store environment variables, and these can contain API keys, credentials, internal file paths, database paths, tokens for AWS and other cloud services, and even CHAINLIT_AUTH_SECRET, a secret that’s used to sign authentication tokens when authentication is enabled.On top of that, if LangChain is used as the orchestration layer behind Chainlit and caching is enabled, user prompts sent to the LLM and the corresponding responses are saved to a file called .chainlit/.langchain.db. This file stores prompts across users and tenants, so attackers could exfiltrate it periodically to obtain sensitive information. Zafran’s proof-of-concept exploit involved leaking this file.
Cross-site request forgery: The second vulnerability (CVE-2026-22218) uses the same custom element as an attack vector but exploits it in a different way, through the URL property. By setting this field, attackers can force the server to trigger a request to the specified URL to fetch its contents and save it in the database.Chainlit uses PostgreSQL by default but can also use SQLAlchemy with different backends such as SQLite or cloud storage providers such as AWS S3 or Azure Blobs. By exploiting this vulnerability, attackers can trigger a cross-site request forgery (SSRF) to obtain credentials.”If Chainlit is deployed on an AWS EC2 instance with IMDSv1 enabled, the SSRF vulnerability can be used to access 169.254.169.254/latest/meta-data/iam/security-credentials/ and retrieve role endpoints, allowing lateral movement within the cloud account,” the researchers said.By combining these two flaws, attackers can extract a lot of information and credentials but also the database itself or source code files from the application that might contain custom code.”Once cloud credentials or IAM tokens are obtained from the server, the attacker is no longer limited to the application,” the researchers wrote in their report. “They gain access to the cloud environment behind it. Storage buckets, secrets managers, LLM, internal data, and other cloud resources may become accessible to an attacker.”The Zafran report contains signatures for the Snort network intrusion detection system and for the Cloudflare web application firewall, which can be used to block attack attempts until the applications are updated to a patched Chainlit version.
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