CVE-2026-49859 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...

CVE-2026-49859

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...

CVE-2026-49859

CVE-2026-49859 affects Deno before version 2.8.1. The bug occurs in fetch() where Deno checked the destination hostname against --deny-net rules but did not re-check the IP addresses that the hostname resolves to, allowing an attacker-controlled domain that passes the hostname check to resolve to...

CVE-2026-49859 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...

EUVD-2026-38541

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...

CVE-2026-49440 Deno: Miller-Rabin Primality Test Allows Zero Rounds

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrimecandidate, options, callback and crypto.checkPrimeSynccandidate, 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 ...

CVE-2026-49440

Summary: CVE-2026-49440 affects Deno’s crypto.primality tests when using default options (checks=0) for checkPrime/checkPrimeSync, causing some composites to be reported as prime due to zero Miller-Rabin rounds. This occurs in the node:crypto path and related op_node_check_prime implementations; ...

CVE-2026-49440 Deno: Miller-Rabin Primality Test Allows Zero Rounds

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrimecandidate, options, callback and crypto.checkPrimeSynccandidate, 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 ...

CVE-2026-49440 Deno: Miller-Rabin Primality Test Allows Zero Rounds

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrimecandidate, options, callback and crypto.checkPrimeSynccandidate, 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 ...

CVE-2026-49440

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrimecandidate, options, callback and crypto.checkPrimeSynccandidate, 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 ...

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

Summary 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 ASCI...

GHSA-X2QC-CMH9-F4HF Deno: Denial of service via non-ASCII bytes in WebSocket response headers

Summary 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 ASCI...

PT-2026-50601

Name of the Vulnerable Software and Affected Versions Deno versions prior to 2.7.5 Description A Deno program opening a client WebSocket connection can be crashed by a remote server. During the WebSocket handshake response, Deno parsed the 'Sec-WebSocket-Protocol' and 'Sec-WebSocket-Extensions'...

GHSA-8XPQ-CJCF-3WH9 Deno: Permission Bypass via Unicode Normalization Mismatch on macOS (APFS)

Summary 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...

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

Summary 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...

GHSA-968W-XFQW-VP9Q Deno: BYONM module resolution allows `package.json` main path traversal to bypass `--allow-read` restrictions

Summary When Deno was run in BYONM mode nodeModulesDir: "manual", the module resolver did not validate that a package's resolved entrypoint stayed within its nodemodules// directory. A malicious package.json whose main field contained .. segments was able to resolve to an arbitrary path on disk,...

GHSA-V8FW-85R8-5M23 Deno: Node TCPWrap numeric hostname aliases bypass --deny-net resolved-IP deny checks

Summary Deno's network permission model is designed so that --deny-net rules apply to the resolved IP address of a destination, not just the literal string supplied by the caller. That means --deny-net=127.0.0.1 or --deny-net=127.0.0.0/8 is expected to block any attempt to reach loopback,...

GHSA-9XG4-QHM4-G43W Deno: Miller-Rabin Primality Test Allows Zero Rounds

Summary node:crypto.checkPrimecandidate, options, callback and crypto.checkPrimeSynccandidate, 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...

GHSA-7XH3-MHG9-JCW8 Deno: Command Injection via spawnSync & spawn on Windows

Summary Deno's node:childprocess 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 such as &, |, , ^, !, , , and did not neutralize %...

GHSA-4C8G-JVCX-V4HV Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access

Summary In Deno, 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...