Haxx: Security Vulnerabilities
libcurl's ASN1 parser code has the `GTime2str()` function, used for parsing an
ASN.1 Generalized Time field. If given an syntactically incorrect field, the
parser might end up using -1 for the length of the *time fraction*, leading to
a `strlen()` getting performed on a pointer to a heap buffer area that is not
(purposely) null terminated.
This flaw most likely leads to a crash, but can also lead to heap contents
getting returned to the application when
[CURLINFO_CERTINFO](https://curl.se/libcurl/c/CURLINFO_CERTINFO.html) is used.
CVSS Score
6.5
EPSS Score
0.008
Published
2024-07-31
libcurl's ASN1 parser has this utf8asn1str() function used for parsing an ASN.1 UTF-8 string. Itcan detect an invalid field and return error. Unfortunately, when doing so it also invokes `free()` on a 4 byte localstack buffer. Most modern malloc implementations detect this error and immediately abort. Some however accept the input pointer and add that memory to its list of available chunks. This leads to the overwriting of nearby stack memory. The content of the overwrite is decided by the `free()` implementation; likely to be memory pointers and a set of flags. The most likely outcome of exploting this flaw is a crash, although it cannot be ruled out that more serious results can be had in special circumstances.
CVSS Score
7.5
EPSS Score
0.013
Published
2024-07-24
libcurl's URL API function
[curl_url_get()](https://curl.se/libcurl/c/curl_url_get.html) offers punycode
conversions, to and from IDN. Asking to convert a name that is exactly 256
bytes, libcurl ends up reading outside of a stack based buffer when built to
use the *macidn* IDN backend. The conversion function then fills up the
provided buffer exactly - but does not null terminate the string.
This flaw can lead to stack contents accidently getting returned as part of
the converted string.
CVSS Score
4.3
EPSS Score
0.01
Published
2024-07-24
When a protocol selection parameter option disables all protocols without adding any then the default set of protocols would remain in the allowed set due to an error in the logic for removing protocols. The below command would perform a request to curl.se with a plaintext protocol which has been explicitly disabled. curl --proto -all,-http http://curl.se The flaw is only present if the set of selected protocols disables the entire set of available protocols, in itself a command with no practical use and therefore unlikely to be encountered in real situations. The curl security team has thus assessed this to be low severity bug.
CVSS Score
3.5
EPSS Score
0.008
Published
2024-03-27
libcurl skips the certificate verification for a QUIC connection under certain conditions, when built to use wolfSSL. If told to use an unknown/bad cipher or curve, the error path accidentally skips the verification and returns OK, thus ignoring any certificate problems.
CVSS Score
6.3
EPSS Score
0.002
Published
2024-03-27
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
0.02
Published
2024-03-27
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