Deno versions 2.7.0 through 2.9.7 on Windows have a critical OS command injection vulnerability in the node:child_process module. The vulnerability arises because shell arguments are escaped incorrectly for the shell type, allowing attackers to inject arbitrary OS commands when untrusted input is passed with the shell option. This can lead to arbitrary command execution with the privileges of the Deno process.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.5, a Deno program that opens a client WebSocket connection could be crashed by the remote server. While handling the WebSocket handshake response, Deno parsed the Sec-WebSocket-Protocol and Sec-WebSocket-Extensions response headers in a way that assumed their bytes were always printable ASCII. A response header containing non-visible-ASCII bytes (0x80-0xFF) caused a panic that aborted the entire Deno process. This vulnerability is fixed in 2.7.5.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. From 2.0.0 until 2.7.8, a flaw in Deno's Node.js tls compatibility layer could cause a TLS client to transmit application data in plaintext after a connection retry. When `autoSelectFamily was enabled and the first address-family attempt failed, the socket reinitialization path reused a stale TLS upgrade hook that was bound to the original, failed handle. As a result, the replacement TCP connection was never upgraded to TLS, and any data the application wrote before the secureConnect event travelled over the network unencrypted. A network attacker positioned to cause the initial connection attempt to fail (for example, by dropping IPv6 traffic on a dual-stack host) could deterministically trigger the fallback path and observe or tamper with traffic that the application believed was TLS-protected. This vulnerability is fixed in 2.7.8.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.14, Deno's permission system enforces filesystem and execution restrictions by comparing the requested path against the path supplied to --deny-read, --deny-write, --deny-run, or --deny-ffi. On macOS, that comparison was done at the raw-byte level while the APFS filesystem treats different Unicode spellings of the same name as the same file. That means a program could reach a denied path by spelling it differently than the deny rule. This vulnerability is fixed in 2.7.14.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.10, Deno's node:child_process implementation provided an escapeShellArg() helper used when callers passed shell: true to spawn / spawnSync / exec and friends. On Windows, the helper failed to quote arguments that contained cmd.exe metacharacters and did not neutralize % (which cmd.exe expands even inside double-quoted strings). An attacker who controlled any portion of an argument passed to such a call could inject arbitrary additional commands into the spawned cmd.exe invocation. This vulnerability is fixed in 2.7.10.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.12, when Deno was run in BYONM mode (nodeModulesDir: "manual"), the module resolver did not validate that a package's resolved entrypoint stayed within its node_modules/<pkg>/ directory. A malicious package.json whose main field contained .. segments was able to resolve to an arbitrary path on disk, and the resolver then read that file without consulting the --allow-read allowlist. This let a require("evil-pkg") call return the contents of a file that a direct Deno.readTextFileSync(...) call would have been blocked from reading. This vulnerability is fixed in 2.7.12.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.0, the Node.js compatibility TCP path checked the permission against the original hostname string before resolution and then did not re-check after resolution. A caller could therefore pass a numeric alias of an IP address (for example the decimal integer 2130706433 or the hex form 0x7f000001, both of which resolve to 127.0.0.1) and reach the denied destination through node:net.connect or node:http.request's { host, port } options form. This vulnerability is fixed in 2.8.0.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, environment access is gated by the env permission. You can deny it with --deny-env, or restrict it to a specific allowlist with --allow-env=FOO,BAR. The expectation is that a program running without env permission cannot change process.env. process.loadEnvFile() (the Node-compatible API for loading variables from a .env file) does not honor this. It only checks that the program has read permission for the dotenv file, then writes every key in that file into the process environment — even when env access is denied. In effect, --allow-read plus a writable or attacker-controlled .env file is enough to defeat --deny-env. This vulnerability is fixed in 2.8.1.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, Deno checked the destination hostname against --deny-net rules but did not re-check the IP addresses that hostname resolved to. An attacker-controlled script could use a specially crafted domain name that passes the hostname check yet resolves to a denied IP, bypassing the network restriction entirely. This vulnerability is fixed in 2.8.1.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when fetch() was called, Deno checked the destination hostname against --deny-net rules but did not re-check the IP addresses that hostname resolved to. An attacker-controlled script could use a specially crafted domain name that passes the hostname check yet resolves to a denied IP, bypassing the network restriction entirely. This vulnerability is fixed in 2.8.1.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrime(candidate[, options][, callback]) and crypto.checkPrimeSync(candidate[, options]) ran no Miller-Rabin rounds at all when the caller left options.checks at its default of 0. In that mode, the only test applied to the candidate was trial division by the primes up to 17,863. Any composite whose smallest prime factor exceeds that bound — for example the product of two primes just above it, such as 17,881 × 17,891 — was reported as true ("probably prime"). The same divergence affected the lower-level op_node_check_prime / op_node_check_prime_bytes paths that the polyfill calls into. This vulnerability is fixed in 2.8.1.
CVE-2026-32260 is a high-severity OS command injection vulnerability in Deno versions 2.7.0 and 2.7.1 affecting the node:child_process polyfill when used with shell: true. The flaw arises from improper sanitization of arguments containing $VAR patterns, where double quotes are used instead of single quotes, allowing backtick command substitution in POSIX shells. This enables attackers controlling spawn or spawnSync arguments to execute arbitrary OS commands, bypassing Deno's permission system. The vulnerability was introduced as a regression after a previous fix (CVE-2026-27190) and is resolved in version 2.7.2.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.6.8, a command injection vulnerability exists in Deno's node:child_process implementation. This vulnerability is fixed in 2.6.8.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Before 2.5.6, a prior patch aimed to block spawning Windows batch/shell files by returning an error when a spawned path’s extension matched .bat or .cmd. That check performs a case-sensitive comparison against lowercase literals and therefore can be bypassed when the extension uses alternate casing (for example .BAT, .Bat, etc.). This vulnerability is fixed in 2.5.6.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Before 2.6.0, node:crypto doesn't finalize cipher. The vulnerability allows an attacker to have infinite encryptions. This can lead to naive attempts at brute forcing, as well as more refined attacks with the goal to learn the server secrets. This vulnerability is fixed in 2.6.0.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Versions prior to 2.5.3 and 2.2.15 are vulnerable to Command Line Injection attacks on Windows when batch files are executed. In Windows, ``CreateProcess()`` always implicitly spawns ``cmd.exe`` if a batch file (.bat, .cmd, etc.) is being executed even if the application does not specify it via the command line. This makes Deno vulnerable to a command injection attack on Windows. Versions 2.5.3 and 2.2.15 fix the issue.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. In versions prior to 2.5.3 and 2.2.15, `Deno.FsFile.prototype.stat` and `Deno.FsFile.prototype.statSync` are not limited by the permission model check `--deny-read=./`. It's possible to retrieve stats from files that the user do not have explicit read access to (the script is executed with `--deny-read=./`). Similar APIs like `Deno.stat` and `Deno.statSync` require `allow-read` permission, however, when a file is opened, even with file-write only flags and deny-read permission, it's still possible to retrieve file stats, and thus bypass the permission model. Versions 2.5.3 and 2.2.15 fix the issue.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. In versions prior to 2.5.3 and 2.2.15, `Deno.FsFile.prototype.utime` and `Deno.FsFile.prototype.utimeSync` are not limited by the permission model check `--deny-write=./`. It's possible to change to change the access (`atime`) and modification (`mtime`) times on the file stream resource even when the file is opened with `read` only permission (and `write`: `false`) and file write operations are not allowed (the script is executed with `--deny-write=./`). Similar APIs like `Deno.utime` and `Deno.utimeSync` require `allow-write` permission, however, when a file is opened, even with read only flags and deny-write permission, it's still possible to change the access (`atime`) and modification (`mtime`) times, and thus bypass the permission model. Versions 2.5.3 and 2.2.15 fix the issue.
@std/toml is the Deno Standard Library. Prior to version 1.0.9, an attacker can pollute the prototype chain in Node.js runtime and Browser when parsing untrusted TOML data, thus achieving Prototype Pollution (PP) vulnerability. This is because the library is merging an untrusted object with an empty object, which by default the empty object has the prototype chain. This issue has been patched in version 1.0.9.
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Starting in version 2.2.0 and prior to versions 2.2.5, it is possible to bypass Deno's permission read/write db permission check by using `ATTACH DATABASE` statement. Version 2.2.5 contains a patch for the issue.