Vulnerabilidades do Denoland Deno

CVE-2026-55517 Média · 4.3 CWE-248 23/06/2026

Deno: Denial of service via non-ASCII bytes in WebSocket response headers

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.

CVE-2026-49983 Média · 5.2 CWE-863 23/06/2026

Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access

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.

CVE-2026-49860 Média · 5.2 CWE-918 23/06/2026

Deno: WebSocket API sandbox bypass via missing post-DNS check

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.

CVE-2026-49859 Média · 5.2 CWE-693 23/06/2026

Deno: `fetch()` API sandbox bypass via missing DNS resolution check

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.

CVE-2026-49440 Alta · 7.4 CWE-325 23/06/2026

Deno: Miller-Rabin Primality Test Allows Zero Rounds

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-2026-49411 Média · 6.5 CWE-284 23/06/2026

Deno Node TCPWrap numeric hostname aliases bypass --deny-net resolved-IP deny checks

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.

CVE-2026-49406 Média · 5.5 CWE-22 23/06/2026

Deno: BYONM module resolution allows `package.json` main path traversal to bypass `--allow-read` restrictions

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.

CVE-2026-49402 Alta · 8.1 CWE-78 23/06/2026

Deno: Command Injection via spawnSync & spawn on Windows

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.

CVE-2026-49401 Alta · 8.4 CWE-41 23/06/2026

Deno Permission Bypass via Unicode Normalization Mismatch on macOS (APFS)

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.

CVE-2026-44726 Crítica · 9.1 CWE-319 23/06/2026

Deno: transmissão em texto puro na camada TLS de compatibilidade com Node.js após nova tentativa de conexão (CWE-319)

O Deno é um runtime de JavaScript, TypeScript e WebAssembly. Da versão 2.0.0 até a 2.7.8, uma falha na camada de compatibilidade tls do Node.js do Deno podia fazer com que um cliente TLS transmitisse dados de aplicação em texto puro após uma nova tentativa de conexão. Quando autoSelectFamily estava habilitado e a primeira tentativa de família de endereços falhava, o caminho de reinicialização do socket reutilizava um hook de upgrade TLS obsoleto, vinculado ao handle original que havia falhado. Como resultado, a conexão TCP de substituição nunca era atualizada para TLS, e quaisquer dados que a aplicação escrevesse antes do evento secureConnect trafegavam pela rede sem criptografia. Um atacante de rede posicionado para fazer a tentativa inicial de conexão falhar (por exemplo, bloqueando tráfego IPv6 em um host dual-stack) poderia acionar de forma determinística o caminho de fallback e observar ou adulterar tráfego que a aplicação acreditava estar protegido por TLS. Esta vulnerabilidade está corrigida na 2.7.8.

CVE-2026-32260 Crítica · 9.8 CWE-78 12/03/2026

Command Injection via incomplete shell metacharacter blocklist in node:child_process (bypass of CVE-2026-27190 fix)

Deno is a JavaScript, TypeScript, and WebAssembly runtime. From 2.7.0 to 2.7.1, A command injection vulnerability exists in Deno's node:child_process polyfill (shell: true mode) that bypasses the fix for CVE-2026-27190. The two-stage argument sanitization in transformDenoShellCommand (ext/node/polyfills/internal/child_process.ts) has a priority bug: when an argument contains a $VAR pattern, it is wrapped in double quotes (L1290) instead of single quotes. Double quotes in POSIX sh do not suppress backtick command substitution, allowing injected commands to execute. An attacker who controls arguments passed to spawnSync or spawn with shell: true can execute arbitrary OS commands, bypassing Deno's permission system. This vulnerability is fixed in 2.7.2.

CVE-2026-27190 Crítica · 9.8 CWE-78 20/02/2026

Deno has a Command Injection via Incomplete shell metacharacter blocklist in node:child_process

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.

CVE-2026-22864 Crítica · 9.8 CWE-77 15/01/2026

Deno has an incomplete fix for command-injection prevention on Windows — case-insensitive extension bypass

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.

CVE-2026-22863 Alta · 7.5 CWE-325 15/01/2026

Deno node:crypto doesn't finalize cipher

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.

CVE-2025-61787 Alta · 8.1 CWE-77 07/10/2025

Deno is Vulnerable to Command Injection on Windows During Batch File Execution

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.

CVE-2025-61786 Baixa · 3.3 CWE-269 07/10/2025

Deno's --deny-read check does not prevent permission bypass

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.

CVE-2025-61785 Baixa · 3.3 CWE-266 07/10/2025

Deno's --deny-write check does not prevent permission bypass

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.