When asked to use a `.netrc` file for credentials **and** to follow HTTP
redirects, curl could leak the password used for the first host to the
followed-to host under certain circumstances.
This flaw only manifests itself if the netrc file has a `default` entry that
omits both login and password. A rare circumstance.
CVSS Score
3.4
EPSS Score
0.001
Published
2025-02-05
When libcurl is asked to perform automatic gzip decompression of
content-encoded HTTP responses with the `CURLOPT_ACCEPT_ENCODING` option,
**using zlib 1.2.0.3 or older**, an attacker-controlled integer overflow would
make libcurl perform a buffer overflow.
CVSS Score
7.3
EPSS Score
0.003
Published
2025-02-05
When asked to both use a `.netrc` file for credentials and to follow HTTP
redirects, curl could leak the password used for the first host to the
followed-to host under certain circumstances.
This flaw only manifests itself if the netrc file has an entry that matches
the redirect target hostname but the entry either omits just the password or
omits both login and password.
CVSS Score
3.4
EPSS Score
0.002
Published
2024-12-11
When curl is asked to use HSTS, the expiry time for a subdomain might
overwrite a parent domain's cache entry, making it end sooner or later than
otherwise intended.
This affects curl using applications that enable HSTS and use URLs with the
insecure `HTTP://` scheme and perform transfers with hosts like
`x.example.com` as well as `example.com` where the first host is a subdomain
of the second host.
(The HSTS cache either needs to have been populated manually or there needs to
have been previous HTTPS accesses done as the cache needs to have entries for
the domains involved to trigger this problem.)
When `x.example.com` responds with `Strict-Transport-Security:` headers, this
bug can make the subdomain's expiry timeout *bleed over* and get set for the
parent domain `example.com` in curl's HSTS cache.
The result of a triggered bug is that HTTP accesses to `example.com` get
converted to HTTPS for a different period of time than what was asked for by
the origin server. If `example.com` for example stops supporting HTTPS at its
expiry time, curl might then fail to access `http://example.com` until the
(wrongly set) timeout expires. This bug can also expire the parent's entry
*earlier*, thus making curl inadvertently switch back to insecure HTTP earlier
than otherwise intended.
CVSS Score
6.5
EPSS Score
0.005
Published
2024-11-06
When curl is told to use the Certificate Status Request TLS extension, often referred to as OCSP stapling, to verify that the server certificate is valid, it might fail to detect some OCSP problems and instead wrongly consider the response as fine. If the returned status reports another error than 'revoked' (like for example 'unauthorized') it is not treated as a bad certficate.
CVSS Score
6.5
EPSS Score
0.002
Published
2024-09-11
When an application tells libcurl it wants to allow HTTP/2 server push, and the amount of received headers for the push surpasses the maximum allowed limit (1000), libcurl aborts the server push. When aborting, libcurl inadvertently does not free all the previously allocated headers and instead leaks the memory. Further, this error condition fails silently and is therefore not easily detected by an application.
CVSS Score
8.6
EPSS Score
0.015
Published
2024-03-27
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
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
0.005
Published
2023-05-26
A denial of service vulnerability exists in curl <v8.1.0 in the way libcurl provides several different backends for resolving host names, selected at build time. If it is built to use the synchronous resolver, it allows name resolves to time-out slow operations using `alarm()` and `siglongjmp()`. When doing this, libcurl used a global buffer that was not mutex protected and a multi-threaded application might therefore crash or otherwise misbehave.
CVSS Score
5.9
EPSS Score
0.006
Published
2023-05-26
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