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python · tornadoHeads-up

tornado CurlAsyncHTTPClient leaks TLS certs and proxy credentials across requests

CurlAsyncHTTPClient reuses pycurl handles without resetting per-request options, causing client TLS certificates (SSLCERT/SSLKEY) and proxy credentials (PROXYUS

16 Jun 2026Read 1 minSeverity: schedule it

What changed

CurlAsyncHTTPClient reuses pycurl handles without resetting per-request options, causing client TLS certificates (SSLCERT/SSLKEY) and proxy credentials (PROXYUSERPWD) to leak across requests.

Who it affects

Applications using CurlAsyncHTTPClient with per-request client_cert/client_key or proxy_username/proxy_password on a shared client instance.

What to do today

Upgrade to a patched version once available, or manually call curl.reset() before each request in _curl_setup_request.

The trail
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