CVE-2026-121425

Nodemailer's address parser parses comma-separated addresses in quadratic time (O(n²)) in the number of addresses. A single crafted address string (e.g., To, Cc, Bcc, From, Reply-To) can cause significant slowdown.

Nodemailer's SMTP client response parser reassembles multiline server replies by appending each continuation line onto a single response-queue entry and re-testing whether it is still a partial reply on every line. The partial-response test performs string operations per line, which can lead to inefficient processing.

Nodemailer's address parser has three published, patched fixes for RFC 5322 comment handling inside an addr-spec. The description covers earlier issues with glued domain atoms and quoted local parts, plus related ReDoS fixes.

A vulnerability in the Nodemailer library allows header injection via the `list.*.comment` field, which is not sanitized for CR (`\r`) and LF (`\n`) characters. An attacker can supply a malicious value in this field, leading to email header spoofing.

A vulnerability in Nodemailer allows bypassing the `disableFileAccess` and `disableUrlAccess` options when using `jsonTransport`. While the normal MIME streaming path enforces these restrictions, `jsonTransport` serializes the message in a way that bypasses them, potentially enabling access to local files or external URLs.

In nodemailer v9.0.0, the message-level `raw` option bypasses `disableFileAccess` and `disableUrlAccess` protections, enabling arbitrary file reads and full SSRF (Server-Side Request Forgery) in the sent message.

Nodemailer disables TLS certificate verification in its internal HTTPS fetch client by setting rejectUnauthorized: false in lib/fetch/index.js. This causes OAuth2 token requests to trust invalid or self-signed HTTPS certificates.

A vulnerability exists in the nodemailer package (npm) affecting versions from 2.7.2 to 10.0.1. Details are not fully described in the provided snippet, but vulnerable versions are confirmed.

Nodemailer's SMTP client applies four regular expressions to a peer's EHLO response to detect supported SASL mechanisms. Each pattern uses overlapping whitespace-matching sub-patterns, producing quadratic (O(n^2)) backtracking on long mechanism names.

Nodemailer's disableFileAccess/disableUrlAccess options are a security sandbox that forbids untrusted message content from reading local files or making outbound HTTP(S) requests. The fix for GHSA-wqvq-jvpq-h66f may be incomplete, allowing bypass of the sandbox.