Golang

(*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, ".") to execute repeatedly on the same input hostname. With a large DNS SAN list, verification costs scaled…

Parsing arbitrary HTML can consume excessive CPU time, possibly leading to denial of service.

An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly removed from the connection's internal state…

On Linux, if the target of Root.Chmod is replaced with a symlink while the chmod operation is in progress, Chmod can operate on the target of the symlink, even when the target lies outside the root. The Linux fchmodat syscall silently ignores the AT_SYMLINK_NOFOLLOW flag, which…

archive/zip uses a super-linear file name indexing algorithm that is invoked the first time a file in an archive is opened. This can lead to a denial of service when consuming a maliciously constructed ZIP archive.

To prevent unexpected untrusted code execution, the Visual Studio Code Go extension is now disabled in Restricted Mode.

If the PATH environment variable contains paths which are executables (rather than just directories), passing certain strings to LookPath ("", ".", and ".."), can result in the binaries listed in the PATH being unexpectedly returned.

On Darwin, building a Go module which contains CGO can trigger arbitrary code execution when using the Apple version of ld, due to usage of the -lto_library flag in a "#cgo LDFLAGS" directive.

When parsing a multipart form (either explicitly with Request.ParseMultipartForm or implicitly with Request.FormValue, Request.PostFormValue, or Request.FormFile), limits on the total size of the parsed form were not applied to the memory consumed while reading a single form…

A malicious HTTP sender can use chunk extensions to cause a receiver reading from a request or response body to read many more bytes from the network than are in the body. A malicious HTTP client can further exploit this to cause a server to automatically read a large amount of…

On Windows, The IsLocal function does not correctly detect reserved device names in some cases. Reserved names followed by spaces, such as "COM1 ", and reserved names "COM" and "LPT" followed by superscript 1, 2, or 3, are incorrectly reported as local. With fix, IsLocal now…

Extremely large RSA keys in certificate chains can cause a client/server to expend significant CPU time verifying signatures. With fix, the size of RSA keys transmitted during handshakes is restricted to <= 8192 bits. Based on a survey of publicly trusted RSA keys, there are…

The ScalarMult and ScalarBaseMult methods of the P256 Curve may return an incorrect result if called with some specific unreduced scalars (a scalar larger than the order of the curve). This does not impact usages of crypto/ecdsa or crypto/ecdh.

An attacker can cause excessive memory growth in a Go server accepting HTTP/2 requests. HTTP/2 server connections contain a cache of HTTP header keys sent by the client. While the total number of entries in this cache is capped, an attacker sending very large keys can cause the…

In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.

In Go before 1.13.13 and 1.14.x before 1.14.5, Certificate.Verify may lack a check on the VerifyOptions.KeyUsages EKU requirements (if VerifyOptions.Roots equals nil and the installation is on Windows). Thus, X.509 certificate verification is incomplete.

When an SSH server authentication callback returned PartialSuccessError with non-nil Permissions, those permissions were silently discarded, potentially dropping certificate restrictions such as force-command after a second factor succeeded. Returning non-nil Permissions with…

The html.Parse function in golang.org/x/net/html has an infinite parsing loop when processing certain inputs, which can lead to denial of service (DoS) if an attacker provides specially crafted HTML content.

During the TLS 1.3 handshake if multiple messages are sent in records that span encryption level boundaries (for instance the Client Hello and Encrypted Extensions messages), the subsequent messages may be processed before the encryption level changes. This can cause some minor…

SSH servers parsing GSSAPI authentication requests do not validate the number of mechanisms specified in the request, allowing an attacker to cause unbounded memory consumption.

SSH Agent servers do not validate the size of messages when processing new identity requests, which may cause the program to panic if the message is malformed due to an out of bounds read.

Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS.

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

If a trusted template author were to write a tag containing an empty 'type' attribute or a 'type' attribute with an ASCII whitespace, the execution of the template would incorrectly escape any data passed into the block.

CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a tag's attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the attribute, the escaper would fail to similarly escape it,…

Parsing a malicious font file can cause excessive memory allocation.

Context was not properly tracked across template branches for JS template literals, leading to possibly incorrect escaping of content when branches were used. Additionally template actions within JS template literals did not properly track the brace depth, leading to incorrect…

Actions which insert URLs into the content attribute of HTML meta tags are not escaped. This can allow XSS if the meta tag also has an http-equiv attribute with the value "refresh". A new GODEBUG setting has been added, htmlmetacontenturlescape, which can be used to disable…

A certificate with a URI which has a IPv6 address with a zone ID may incorrectly satisfy a URI name constraint that applies to the certificate chain. Certificates containing URIs are not permitted in the web PKI, so this only affects users of private PKIs which make use of URIs.

The HTTP client drops sensitive headers after following a cross-domain redirect. For example, a request to a.com/ containing an Authorization header which is redirected to b.com/ will not send that header to b.com. In the event that the client received a subsequent same-domain…

net/http in Go before 1.15.12 and 1.16.x before 1.16.4 allows remote attackers to cause a denial of service (panic) via a large header to ReadRequest or ReadResponse. Server, Transport, and Client can each be affected in some configurations.

A message-forgery issue was discovered in crypto/openpgp/clearsign/clearsign.go in supplementary Go cryptography libraries 2019-03-25. According to the OpenPGP Message Format specification in RFC 4880 chapter 7, a cleartext signed message can contain one or more optional "Hash"…

A bug in the standard library ScalarMult implementation of curve P-256 for amd64 architectures in Go before 1.7.6 and 1.8.x before 1.8.2 causes incorrect results to be generated for specific input points. An adaptive attack can be mounted to progressively extract the scalar…

Previously, resolving relative paths containing parent directory ('..') segments performed string conversions and buffer rewrites on each step, resulting in quadratic time complexity and high memory allocation overhead. Now, path resolution operates on a byte buffer using…

The "go tool pack" subcommand (usually used only by the compiler as an internal tool with known-good inputs) does not sanitize output filenames. Extracting a malicious archive file with the "pack" subcommand can write files to arbitrary locations on the filesystem.

Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.

A malformed DNS message in response to a query can cause the Lookup functions to get stuck in an infinite loop.

Verifying a certificate chain which contains a certificate with an unknown public key algorithm will cause Certificate.Verify to panic. This affects all crypto/tls clients, and servers that set Config.ClientAuth to VerifyClientCertIfGiven or RequireAndVerifyClientCert. The…

Go before 1.16.12 and 1.17.x before 1.17.5 on UNIX allows write operations to an unintended file or unintended network connection as a consequence of erroneous closing of file descriptor 0 after file-descriptor exhaustion.

An unintended cleartext issue exists in Go before 1.8.4 and 1.9.x before 1.9.1. RFC 4954 requires that, during SMTP, the PLAIN auth scheme must only be used on network connections secured with TLS. The original implementation of smtp.PlainAuth in Go 1.0 enforced this…

tar.Reader can allocate an unbounded amount of memory when reading a maliciously-crafted archive containing a large number of sparse regions encoded in the "old GNU sparse map" format.

When using http.CrossOriginProtection, the AddInsecureBypassPattern method can unexpectedly bypass more requests than intended. CrossOriginProtection then skips validation, but forwards the original request path, which may be served by a different handler without the intended…

If errors returned from MarshalJSON methods contain user controlled data, they may be used to break the contextual auto-escaping behavior of the html/template package, allowing for subsequent actions to inject unexpected content into templates.

Go before 1.17.10 and 1.18.x before 1.18.2 has Incorrect Privilege Assignment. When called with a non-zero flags parameter, the Faccessat function could incorrectly report that a file is accessible.

Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello.

When returning errors, functions in the net/textproto package would include its input as part of the error. This might allow an attacker to inject misleading content to errors that are printed or logged.

Decoding a paletted BMP file with an out-of-range palette index results in a panic when accessing pixels in the invalid image.