curl's WebSocket code did not update the 32-bit mask pattern for each new
outgoing frame as the specification says. Instead it used a fixed mask that
persisted and was used throughout the entire connection.
A predictable mask pattern allows for a malicious server to induce traffic
between the two communicating parties that could be interpreted by an involved
proxy (configured or transparent) as genuine, real, HTTP traffic with content
and thereby poison its cache. That cached poisoned content could then be
served to all users of that proxy.
CVSS Score
5.3
EPSS Score
0.005
Published
2025-09-12
Due to a mistake in libcurl's WebSocket code, a malicious server can send a
particularly crafted packet which makes libcurl get trapped in an endless
busy-loop.
There is no other way for the application to escape or exit this loop other
than killing the thread/process.
This might be used to DoS libcurl-using application.
CVSS Score
7.5
EPSS Score
0.014
Published
2025-06-07
libcurl accidentally skips the certificate verification for QUIC connections when connecting to a host specified as an IP address in the URL. Therefore, it does not detect impostors or man-in-the-middle attacks.
CVSS Score
6.5
EPSS Score
0.003
Published
2025-05-28
libcurl supports *pinning* of the server certificate public key for HTTPS transfers. Due to an omission, this check is not performed when connecting with QUIC for HTTP/3, when the TLS backend is wolfSSL. Documentation says the option works with wolfSSL, failing to specify that it does not for QUIC and HTTP/3. Since pinning makes the transfer succeed if the pin is fine, users could unwittingly connect to an impostor server without noticing.
CVSS Score
4.8
EPSS Score
0.003
Published
2025-05-28
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