GHSA-QPPV-J76H-2RPX

Tornado interprets -, +, and _ in chunk length and Content-Length values, which are not allowed by the HTTP RFCs. This can result in request smuggling when Tornado is deployed behind certain proxies that interpret those non-standard characters differently. This is known to apply to older versions of haproxy, although the current release is not affected.

Details

Tornado uses the int constructor to parse the values of Content-Length headers and chunk lengths in the following locations:

tornado/http1connection.py:445

            self._expected_content_remaining = int(headers["Content-Length"])

tornado/http1connection.py:621

                content_length = int(headers["Content-Length"])  # type: Optional[int]

tornado/http1connection.py:671

            chunk_len = int(chunk_len_str.strip(), 16)

Because int("0_0") == int("+0") == int("-0") == int("0"), using the int constructor to parse and validate strings that should contain only ASCII digits is not a good strategy.

Kodem intelligence

1. What is GHSA-QPPV-J76H-2RPX? GHSA-QPPV-J76H-2RPX is a medium-severity security vulnerability in tornado (pip), affecting versions < 6.3.3. It is fixed in 6.3.3.
2. Which versions of tornado are affected by GHSA-QPPV-J76H-2RPX? tornado (pip) versions < 6.3.3 is affected.
3. Is there a fix for GHSA-QPPV-J76H-2RPX? Yes. GHSA-QPPV-J76H-2RPX is fixed in 6.3.3. Upgrade to this version or later.
4. Is GHSA-QPPV-J76H-2RPX exploitable, and should I be worried? Whether GHSA-QPPV-J76H-2RPX 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
5. What actually determines whether GHSA-QPPV-J76H-2RPX 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.
6. How do I fix GHSA-QPPV-J76H-2RPX? Upgrade tornado to 6.3.3 or later.