cURL libcurl could allow a remote attacker to bypass security restrictions, caused by a flaw when using OCSP stapling to validate server cerficate. By sending a specially crafted request, an attacker could exploit this vulnerability to establish the connection even if the certificate is revoked.

An issue was discovered in libexpat before 2.6.4. There is a crash within the XMLResumeParser function because XMLStopParser can stop/suspend an unstarted parser.

Accounts. The issue was addressed with improved checks.

Accounts. The issue was addressed with improved checks.

After a failed cache insertion, addgetnetgrentX tries to send the non-existing response after the not-found header.

In addinnetgrX, addgetnetgrentX may have produced a NULL result, indicating a not-found status, but this is not handled in the subsequent code that prepares the record that will be sent out to the client.

Reference: https://sourceware.org/bugzilla/showbug.cgi?id=31678

A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks two threads sharing the same HSTS data could end up doing a double-free or use-after-free.

An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However certain FTP settings such as CURLOPTFTPACCOUNT CURLOPTFTPALTERNATIVETOUSER CURLOPTFTPSSLCCC and CURLOPTUSESSL were not included in the configuration match checks causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer potentially allowing unauthorized access to sensitive information.

An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPTGSSAPIDELEGATION option. This vulnerability affects krb5/kerberos/negotiate/GSSAPI transfers and could potentially result in unauthorized access to sensitive information. The safest option is to not reuse connections if the CURLOPTGSSAPIDELEGATION option has been changed.

A cleartext transmission of sensitive information vulnerability exists in curl <v7.88.0 that could cause HSTS functionality to behave incorrectly when multiple URLs are requested in parallel. Using its HSTS support, curl can be instructed to use HTTPS instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. This HSTS mechanism would however surprisingly fail when multiple transfers are done in parallel as the HSTS cache file gets overwritten by the most recentlycompleted transfer. A later HTTP-only transfer to the earlier host name would then not get upgraded properly to HSTS.

An allocation of resources without limits or throttling vulnerability exists in curl <v7.88.0 based on the "chained" HTTP compression algorithms, meaning that a server response can be compressed multiple times and potentially with differentalgorithms. The number of acceptable "links" in this "decompression chain" wascapped, but the cap was implemented on a per-header basis allowing a maliciousserver to insert a virtually unlimited number of compression steps simply byusing many headers. The use of such a decompression chain could result in a "malloc bomb", making curl end up spending enormous amounts of allocated heap memory, or trying to and returning out of memory errors.

A flaw has been identified in glibc. In an uncommon situation, the gaihinet function may use memory that has been freed, resulting in an application crash. This issue is only exploitable when the getaddrinfo function is called and the hosts database in /etc/nsswitch.conf is configured with SUCCESS=continue or SUCCESS=merge.

A flaw was found in the exFAT driver of the Linux kernel. The vulnerability exists in the implementation of the file name reconstruction function, which is responsible for reading file name entries from a directory index and merging file name parts belonging to one file into a single long file name. Since the file name characters are copied into a stack variable, a local privileged attacker could use this flaw to overflow the kernel stack.

A flaw was found in glibc. When the getaddrinfo function is called with the AFUNSPEC address family and the system is configured with no-aaaa mode via /etc/resolv.conf, a DNS response via TCP larger than 2048 bytes can potentially disclose stack contents through the function returned address data, and may cause a crash.

A flaw in the Linux Kernel found in the GFS2 file system. On corrupted gfs2 file systems the evict code can try to reference the journal descriptor structure, jdesc, after it has been freed and set to NULL. It can lead to null pointer dereference when gfs2transbegin being called and then fail ingfs2evictinode().

Reference: https://listman.redhat.com/archives/cluster-devel/2023-April/023914.html

Last updated 25 April 2025

An issue was discovered in the Linux kernel through 5.18.14. xfrmexpandpolicies in net/xfrm/xfrmpolicy.c can cause a refcount to be dropped twice.

curl can be told to parse a .netrc file for credentials. If that file endsin a line with 4095 consecutive non-white space letters and no newline, curlwould first read past the end of the stack-based buffer, and if the readworks, write a zero byte beyond its boundary.This will in most cases cause a segfault or similar, but circumstances might also cause different outcomes.If a malicious user can provide a custom netrc file to an application or otherwise affect its contents, this flaw could be used as denial-of-service.

A vulnerability was found in curl. This issue occurs because the number of acceptable "links" in the "decompression chain" was unbounded, allowing a malicious server to insert a virtually unlimited number of compression steps. This flaw leads to a denial of service, either by mistake or by a malicious actor.

A vulnerability was found in curl. This issue occurs because it mishandles message verification failures when curl does FTP transfers secured by krb5. This flaw makes it possible for a Man-in-the-middle attack to go unnoticed and allows data injection into the client.

A malicious server can serve excessive amounts of Set-Cookie: headers in a HTTP response to curl and curl < 7.84.0 stores all of them. A sufficiently large amount of (big) cookies make subsequent HTTP requests to this, or other servers to which the cookies match, create requests that become larger than the threshold that curl uses internally to avoid sending crazy large requests (1048576 bytes) and instead returns an error.This denial state might remain for as long as the same cookies are kept, match and haven't expired. Due to cookie matching rules, a server on foo.example.com can set cookies that also would match for bar.example.com, making it it possible for a "sister server" to effectively cause a denial of service for a sibling site on the same second level domain using this method.

Using its HSTS support, curl can be instructed to use HTTPS directly insteadof using an insecure clear-text HTTP step even when HTTP is provided in theURL. This mechanism could be bypassed if the host name in the given URL used atrailing dot while not using one when it built the HSTS cache. Or the otherway around - by having the trailing dot in the HSTS cache and not using thetrailing dot in the URL.

libcurl wrongly allows cookies to be set for Top Level Domains (TLDs) if thehost name is provided with a trailing dot.curl can be told to receive and send cookies. curl's "cookie engine" can bebuilt with or without Public Suffix Listawareness. If PSL support not provided a more rudimentary check exists to atleast prevent cookies from being set on TLDs. This check was broken if thehost name in the URL uses a trailing dot.This can allow arbitrary sites to set cookies that then would get sent to adifferent and unrelated site or domain.

An insufficiently protected credentials vulnerability exists in curl 4.9 to and include curl 7.82.0 are affected that could allow an attacker to extract credentials when follows HTTP(S) redirects is used with authentication could leak credentials to other services that exist on different protocols or port numbers.

A insufficiently protected credentials vulnerability in fixed in curl 7.83.0 might leak authentication or cookie header data on HTTP redirects to the same host but another port number.

A flaw was found in OpenSSL's Online Certificate Status Protocol (OCSP) response functionality in the signer certificate verification routines. This flaw could result in a linked application falsely believing that an x.509 Digital Certificate is either "good" or "unknown" when revoked and requires that the application use a non-default configuration. This vulnerability leads to an issue with data integrity and confidentiality.

Last updated 24 July 2024

A flaw was found in curl. The flaw lies in how curl handles cached or pipelined responses that it receives from either a IMAP, POP3, SMTP or FTP server before the TLS upgrade using STARTTLS. In such a scenario curl even after upgrading to TLS would trust these cached responses treating them as valid and authenticated and use them. An attacker could potentially use this flaw to carry out a Man-In-The-Middle attack. The highest threat from this vulnerability is to data confidentiality.

A flaw was found in the way curl handled telnet protocol option for sending environment variables, which could lead to sending of uninitialized data from a stack-based buffer to the server. This issue leads to potentially revealing sensitive internal information to the server using a clear-text network protocol.

A flaw was found in curl in the way curl handles a file hash mismatch after downloading content using the Metalink feature. This flaw allows malicious actors controlling a hosting server to trick users into downloading malicious content. The highest threat from this vulnerability is to integrity.

A flaw was found in curl in the way curl handles credentials when downloading content using the Metalink feature. This flaw allows malicious actors controlling a hosting server to gain access to credentials provided while downloading content without the user's knowledge. The highest threat from this vulnerability is to confidentiality.