CVE-2026-21637
HighSummary
A vulnerability in Node.js TLS error handling allows remote attackers to crash or exhaust resources of a TLS server when `pskCallback` or `ALPNCallback` are in use. Synchronous exceptions thrown during these callbacks bypass standard TLS error handling paths, leading to immediate process termination or silent file descriptor leaks that eventually cause denial of service.
Risk Assessment
The risk is the possibility of a remote DoS attack on a TLS server, which can result in service disruption or resource exhaustion, impacting application availability.
Recommendation
It is recommended to immediately update Node.js to a patched version and, if possible, temporarily disable or safely wrap PSK and ALPN callbacks in server code.
Other vulnerabilities in Node.js
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A bug has been identified in Node.js error handling where 'Maximum call stack size exceeded' errors become uncatchable when `async_hooks.createHook()` is enabled. Instead of reaching `process.on('uncaughtException')`, the process terminates, making the crash unrecoverable. Applications relying on `AsyncLocalStorage` (v22, v20) or `async_hooks.createHook()` (v24, v22, v20) become vulnerable to denial-of-service crashes triggered by deep recursion under specific conditions.
- CVE-2025-59464High
A memory leak in Node.js's OpenSSL integration occurs when converting X.509 certificate fields to UTF-8 without freeing the allocated buffer. Applications calling socket.getPeerCertificate(true) leak memory per certificate field, allowing remote clients to trigger steady memory growth through repeated TLS connections.
- CVE-2015-7384High
Node.js versions 4.0.0, 4.1.0, and 4.1.1 allow remote attackers to cause a denial of service.
- CVE-2017-14849High
Node.js 8.5.0 before 8.6.0 allows remote attackers to access unintended files, because a change to '..' handling was incompatible with the pathname validation used by unspecified community modules.
- CVE-2017-11499High
Node.js versions from 4.0 to 4.8.3, all 5.x versions, and versions 6.0 to 6.11.0, 7.0 to 7.10.0, and 8.0 to 8.1.3 were susceptible to hash flooding DoS attacks. This was due to the HashTable seed being constant across a given released version of Node.js.
- CVE-2016-2216High
The HTTP header parsing code in Node.js in versions 0.10.x before 0.10.42, 0.11.6 through 0.11.16, 0.12.x before 0.12.10, 4.x before 4.3.0, and 5.x before 5.6.0 allows remote attackers to bypass an HTTP response-splitting protection mechanism via UTF-8 encoded Unicode characters in the HTTP header.
- CVE-2016-2086High
Node.js versions 0.10.x before 0.10.42, 0.12.x before 0.12.10, 4.x before 4.3.0, and 5.x before 5.6.0 are vulnerable to HTTP request smuggling attacks via a crafted Content-Length HTTP header.
- CVE-2015-8027High
Node.js versions 0.12.x before 0.12.9, 4.x before 4.2.3, and 5.x before 5.1.1 do not ensure the availability of a parser for each HTTP socket, allowing remote attackers to cause a denial of service via a pipelined HTTP request.
- CVE-2026-21710High
A flaw in Node.js HTTP request handling causes an uncaught TypeError when a request with a header named __proto__ is received and the application accesses req.headersDistinct. The exception is thrown synchronously inside a property getter and cannot be intercepted by error event listeners.
- CVE-2026-21636Critical
A flaw in Node.js's permission model allows Unix Domain Socket (UDS) connections to bypass network restrictions when `--permission` is enabled. Even without `--allow-net`, attacker-controlled inputs (such as URLs or socketPath options) can connect to arbitrary local sockets via net, tls, or undici/fetch. This breaks the intended security boundary of the permission model and enables access to privileged local services, potentially leading to privilege escalation, data exposure, or local code execution. The issue affects users on version v25.
Original NVD description (English source)
A flaw in Node.js TLS error handling allows remote attackers to crash or exhaust resources of a TLS server when `pskCallback` or `ALPNCallback` are in use. Synchronous exceptions thrown during these callbacks bypass standard TLS error handling paths (tlsClientError and error), causing either immediate process termination or silent file descriptor leaks that eventually lead to denial of service. Because these callbacks process attacker-controlled input during the TLS handshake, a remote client can repeatedly trigger the issue. This vulnerability affects TLS servers using PSK or ALPN callbacks across Node.js versions where these callbacks throw without being safely wrapped.