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Vulnerability details: VCID-wfd1-2za4-1ffa
Vulnerability ID VCID-wfd1-2za4-1ffa
Aliases PYSEC-2019-66
Summary Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk None
Affected and Fixed Packages Package Details
Weaknesses (0)
There are no known CWE.
System Score Found at
There are no known severity scores.
No exploits are available.
There are no known vectors.

No EPSS data available for this vulnerability.

Date Actor Action Source VulnerableCode Version
2026-06-05T16:55:37.636442+00:00 PyPI Importer Import https://osv-vulnerabilities.storage.googleapis.com/PyPI/all.zip 38.6.0