CVE-2023-38545

When processing an HTTP redirect to a URL containing userinfo (a username:password component), curl might erroneously retain and re-transmit the original host's HTTP Negotiate authentication state. Consequently, a malicious server can trigger a redirect containing arbitrary userinfo to force curl to send a freshly minted Kerberos ticket to an untrusted third-party host, effectively bypassing the domain-scoping restrictions normally enforced by the absence of --location-trusted.

When invoked with --remote-header-name (-J), curl fails to preserve its documented anti-clobbering protection if an intermediate 103 Early Hints response precedes the final HTTP response, or if an ETag header is processed before Content-Disposition under --etag-save. This flaw allows an HTTP(S) server to overwrite an existing local file specified in the Content-Disposition header despite the -J non-overwrite constraint.

When writing a long cookie name and value to a Netscape cookie jar, a remote HTTP server can make curl write a record that exceeds its line-length parsing limit. Consequently, any subsequent curl invocation reading from that same cookie jar using --cookie silently aborts parsing prematurely upon encountering the too long line, ignoring all subsequent valid cookies in the file.

When built with wolfSSL, curl can successfully validate a pinned public key hash against a key the TLS peer does not possess. During the TLS handshake, wolfSSL validates the connection, but curl's subsequent re-parsing of the same certificate, tricked by a manipulated validity length field, extracts and matches a different embedded key, incorrectly authorizing the pinned public key.

Enabling CURLOPT_CRLF causes curl to advertise the raw input byte count in the IMAP APPEND {N} literal while transmitting line-ending expanded data. The server reads only N bytes for the payload, causing the remaining overflow bytes to be interpreted and executed as pipelined IMAP commands within the authenticated session.

An authenticated HTTPS origin can supply an HSTS max-age value that the parser accepts but time serialization later fails to process. On 64-bit systems, extreme max-age values compute an absolute expiry that exceeds calendar time structure bounds. During cache saves, the original HSTS file is truncated before writing a temporary replacement; when serialization fails, the temporary file is deleted, leaving an empty or partial cache, and the save error is silently ignored.

Importing an includeSubDomains parent HSTS entry before a longer-lived child entry silently drops the child. Consequently, when the parent expires, the child's valid HSTS policy is lost, causing curl to issue unencrypted HTTP requests rather than upgrading to HTTPS.

When using ambient user credentials, an HTTP request directed to one origin may be dispatched over a connection previously authenticated via Negotiate for a different origin, leaving the request's intended credentials unused.

libcurl's connection cache match function never considers the automatic client certificate option, so a cached, already authenticated Schannel connection can be handed to a transfer redirected to a different origin, even though the code explicitly switched off the auto client cert option for that transfer.

An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password or a Negotiate/Kerberos ticket) to the proxy itself by answering the CONNECT tunnel request with 401 WWW-Authenticate instead of the expected 407 Proxy-Authenticate.