Twisted is an event-based framework for internet applications, supporting Python 3.6+.

Summary An incomplete header-value validation (CWE-444) in the Twisted HTTP server lets a bare carriage return or line feed in a header value hide a following header from the parser. twisted.web.http.HTTPChannel.headerReceived rejects a NUL byte in a header value but not a bare CR or LF, even though RFC 9110 section 5.5 requires a recipient to reject all three. Because the channel splits requests only on CRLF, a value carrying a bare LF and a second header arrives as one line, so the second header is folded into the value and the request is framed with no body. A front-end that treats the bare LF as a line terminator frames the request differently, and the disagreement lets an attacker smuggle a request past it. This is an incomplete fix of the earlier Twisted request-smuggling advisories, which guarded the NUL sibling of this exact check. Details headerReceived splits a header line on the first colon, strips space and tab from the value, and validates it with a single test that rejects only NUL: python twisted/web/http.py HTTPChannel.headerReceived data = data.strip(b" \t") if b"\x00" in data: # NUL rejected; a bare CR or LF is not self.respondToBadRequestAndDisconnect() return…

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curl https://cve.zerocrew.in/api/cve/CVE-2026-115877