Haxx: Security Vulnerabilities
libcurl did not check the server certificate of TLS connections done to a host specified as an IP address, when built to use mbedTLS. libcurl would wrongly avoid using the set hostname function when the specified hostname was given as an IP address, therefore completely skipping the certificate check. This affects all uses of TLS protocols (HTTPS, FTPS, IMAPS, POPS3, SMTPS, etc).
CVSS Score
6.5
EPSS Score
0.001
Published
2024-03-27
curl inadvertently kept the SSL session ID for connections in its cache even when the verify status (*OCSP stapling*) test failed. A subsequent transfer to
the same hostname could then succeed if the session ID cache was still fresh, which then skipped the verify status check.
CVSS Score
5.3
EPSS Score
0.002
Published
2024-02-03
When saving HSTS data to an excessively long file name, curl could end up
removing all contents, making subsequent requests using that file unaware of
the HSTS status they should otherwise use.
CVSS Score
5.3
EPSS Score
0.002
Published
2023-12-12
This flaw allows a malicious HTTP server to set "super cookies" in curl that
are then passed back to more origins than what is otherwise allowed or
possible. This allows a site to set cookies that then would get sent to
different and unrelated sites and domains.
It could do this by exploiting a mixed case flaw in curl's function that
verifies a given cookie domain against the Public Suffix List (PSL). For
example a cookie could be set with `domain=co.UK` when the URL used a lower
case hostname `curl.co.uk`, even though `co.uk` is listed as a PSL domain.
CVSS Score
6.5
EPSS Score
0.004
Published
2023-12-07
This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy
handshake.
When curl is asked to pass along the host name to the SOCKS5 proxy to allow
that to resolve the address instead of it getting done by curl itself, the
maximum length that host name can be is 255 bytes.
If the host name is detected to be longer, curl switches to local name
resolving and instead passes on the resolved address only. Due to this bug,
the local variable that means "let the host resolve the name" could get the
wrong value during a slow SOCKS5 handshake, and contrary to the intention,
copy the too long host name to the target buffer instead of copying just the
resolved address there.
The target buffer being a heap based buffer, and the host name coming from the
URL that curl has been told to operate with.
CVSS Score
9.8
EPSS Score
0.263
Published
2023-10-18
This flaw allows an attacker to insert cookies at will into a running program
using libcurl, if the specific series of conditions are met.
libcurl performs transfers. In its API, an application creates "easy handles"
that are the individual handles for single transfers.
libcurl provides a function call that duplicates en easy handle called
[curl_easy_duphandle](https://curl.se/libcurl/c/curl_easy_duphandle.html).
If a transfer has cookies enabled when the handle is duplicated, the
cookie-enable state is also cloned - but without cloning the actual
cookies. If the source handle did not read any cookies from a specific file on
disk, the cloned version of the handle would instead store the file name as
`none` (using the four ASCII letters, no quotes).
Subsequent use of the cloned handle that does not explicitly set a source to
load cookies from would then inadvertently load cookies from a file named
`none` - if such a file exists and is readable in the current directory of the
program using libcurl. And if using the correct file format of course.
CVSS Score
3.7
EPSS Score
0.003
Published
2023-10-18
When curl retrieves an HTTP response, it stores the incoming headers so that
they can be accessed later via the libcurl headers API.
However, curl did not have a limit in how many or how large headers it would
accept in a response, allowing a malicious server to stream an endless series
of headers and eventually cause curl to run out of heap memory.
CVSS Score
7.5
EPSS Score
0.123
Published
2023-09-15
Integer overflow vulnerability in tool_operate.c in curl 7.65.2 via a large value as the retry delay. NOTE: many parties report that this has no direct security impact on the curl user; however, it may (in theory) cause a denial of service to associated systems or networks if, for example, --retry-delay is misinterpreted as a value much smaller than what was intended. This is not especially plausible because the overflow only happens if the user was trying to specify that curl should wait weeks (or longer) before trying to recover from a transient error.
CVSS Score
3.3
EPSS Score
0.0
Published
2023-08-22
An improper certificate validation vulnerability exists in curl <v8.1.0 in the way it supports matching of wildcard patterns when listed as "Subject Alternative Name" in TLS server certificates. curl can be built to use its own name matching function for TLS rather than one provided by a TLS library. This private wildcard matching function would match IDN (International Domain Name) hosts incorrectly and could as a result accept patterns that otherwise should mismatch. IDN hostnames are converted to puny code before used for certificate checks. Puny coded names always start with `xn--` and should not be allowed to pattern match, but the wildcard check in curl could still check for `x*`, which would match even though the IDN name most likely contained nothing even resembling an `x`.
CVSS Score
5.9
EPSS Score
0.003
Published
2023-05-26
An information disclosure vulnerability exists in curl <v8.1.0 when doing HTTP(S) transfers, libcurl might erroneously use the read callback (`CURLOPT_READFUNCTION`) to ask for data to send, even when the `CURLOPT_POSTFIELDS` option has been set, if the same handle previously wasused to issue a `PUT` request which used that callback. This flaw may surprise the application and cause it to misbehave and either send off the wrong data or use memory after free or similar in the second transfer. The problem exists in the logic for a reused handle when it is (expected to be) changed from a PUT to a POST.
CVSS Score
3.7
EPSS Score
0.006
Published
2023-05-26