Nodemailer vulnerabilities

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 process-global DNS cache is keyed only by `host`, but each cache entry also stores the caller-specific TLS `servername`. When two direct SMTPS transports use the same DNS host with different `tls.servername` values, the first transport's server name is returned to the second.

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 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.

Nodemailer resolves an international (IDN / non-ASCII) recipient domain to a different Punycode label than every UTS-46-conformant parser (web browsers, WHATWG URL Standard, Node's url.domainToASCII, Python's idna). Its address normalizer (_normalizeAddress) may lead to incorrect domain resolution, enabling phishing or message misdirection.

Nodemailer's email-address parser treats an RFC 5322 comment inside the domain as a point to concatenate the surrounding text, rather than as folding whitespace (CFWS) that terminates the domain. This can lead to incorrect parsing, e.g., [email protected](x)evil.c..., potentially redirecting messages or bypassing validation.

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 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.

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 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.

Nodemailer before 8.0.4 is vulnerable to SMTP command injection through the unsanitized envelope.size parameter. When an application passes a custom envelope object with a size property containing CRLF characters to sendMail(), the value is concatenated into the SMTP MAIL FROM command (as SIZE=...) without sanitization, allowing injection of arbitrary SMTP commands such as RCPT TO to silently add attacker-controlled recipients.

Nodemailer from 3.0.0 before 10.0.10 contains a quadratic complexity denial of service vulnerability in the SMTP client reply parser in SMTPConnection._onData and isPartialResponse. A malicious SMTP server or on-path attacker can stream continuation lines without a completion line before authentication, blocking the Node.js event loop and exhausting memory.

Nodemailer from 3.0.0 before 10.0.10 contains a denial of service vulnerability in MessageParser.parseHeaders that allows users to exhaust CPU through quadratic header unfolding. Attackers can supply large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing.

Nodemailer from 3.0.0 before 10.0.13 contains an improper input validation vulnerability in its address parser that fails to strip RFC 5322 comments inside angle-bracket addresses. Attackers can supply recipients like a display name with a parenthesized comment in the domain, so illegal characters reach envelope.to and RCPT TO, causing rejected delivery or parser interpretation conflicts that bypass domain allow-lists.

Nodemailer 3.0.0 before 10.0.13 has a regular expression denial of service in SMTPConnection._actionEHLO, whose four AUTH mechanism detection regexes contain overlapping whitespace sub-patterns that backtrack quadratically. A malicious or man-in-the-middle SMTP server can reply to EHLO with 250-AUTH, a long whitespace run and a non-matching token, blocking the Node.js event loop for tens of seconds to hours before authentication.

Nodemailer before 10.0.2 fails to properly flatten deeply nested arrays in recipient fields such as to, cc, and bcc, allowing attackers to cause stack exhaustion. Attackers can supply a deeply nested JSON recipient array that triggers recursive Array.toString() conversion, exhausting the call stack and terminating the Node.js process.

Nodemailer versions 5.0.0 through 10.0.1 use a process-global DNS cache that is keyed only by the DNS host, while each cache entry also stores the caller-specific TLS servername. When two direct TLS/SMTPS transports (secure: true) resolve the same non-IP host with different tls.servername values, the first transport's servername is returned on the cache hit and overwrites the second transport's explicitly configured value, so Nodemailer sends the wrong SNI value and validates the peer certificate against the wrong identity. In multi-tenant services or SNI-routed SMTP gateways, an attacker who can prime the cache can cause a victim transport to connect to the attacker's TLS virtual host and accept the attacker's certificate even with rejectUnauthorized: true, disclosing the victim's SMTP credentials. Fixed in 10.0.2.

nodemailer before 10.0.6 contains a denial of service vulnerability in the addressparser free-text fallback regex pattern that exhibits quadratic backtracking behavior. Attackers can supply crafted email header values with long whitespace-free runs to block the Node.js event loop for tens of seconds, causing service unavailability.

Nodemailer is a Node.js email-sending library. In versions >= 9.1.0 and < 10.0.9, the address parser (src/addressparser) mishandles addresses whose local-part is a quoted string and that are followed by RFC 5322 comments, allowing trailing comment-separated domain atoms to be retained in the normalized address. For example, the input "user"@example.com(x)evil.com is parsed to the address value '[email protected] evil.com', which contains additional attacker-controlled domain text separated by a literal space. This parsed value is used without further strict recipient validation when the message envelope is built (envelope.to in src/mime-node), so a malformed/ambiguous recipient address can be accepted and placed in the SMTP envelope. Whether this results in delivery to an unintended recipient on real SMTP servers has not been confirmed. The issue is a variant of the RFC 5322 comment parsing problem addressed in GHSA-cc9r-2j5m-2m83, affecting the separate quoted-local-part code path. Version 10.0.9 contains a fix.

Nodemailer before 9.1.0 fails to apply UTS-46 normalization when encoding international domain names, causing the domain resolver to compute a different Punycode A-label than standards-compliant parsers. Attackers can craft recipient addresses with invisible characters or compatibility mappings that pass domain allow-list checks but are delivered to attacker-controlled domains via SMTP.

Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email addresses. A comment closed immediately before a non-break character causes the tokenizer to concatenate the atoms surrounding the comment, so an address like [email protected](x)evil.com is read as the domain good-corp.comevil.com. This can lead to delivery to an attacker-controlled domain. Fixed in 9.1.0.

Nodemailer before 9.1.0 contains a quadratic time complexity vulnerability in the addressparser component that allows remote attackers to cause denial of service by supplying a crafted comma-separated address list. Attackers can send a single email with a large number of addresses to block the Node.js event loop for extended periods, consuming 100% CPU and freezing the process.

Nodemailer versions 9.1.0 and earlier do not honor the disableFileAccess and disableUrlAccess sandbox options when message content is resolved through the public plugin API MailMessage.resolveContent() using the legacy three-argument signature. As a result, plugin or application code can be induced to read arbitrary local files or issue outbound HTTP(S) requests (SSRF), bypassing the enabled sandbox. Fixed in 9.1.1.

Nodemailer versions 9.1.0 through 10.0.4 contain a quadratic time complexity vulnerability in the addressparser component when parsing email addresses with RFC 5322 comments. Attackers can craft malicious email headers with comment-separated atoms to consume excessive CPU and block the Node.js event loop for several seconds, causing denial of service.

Nodemailer versions before 8.0.5 contain an SMTP command injection vulnerability in the transport name option used in EHLO/HELO commands. The name parameter is concatenated directly into SMTP commands without sanitizing carriage return and line feed characters, allowing attackers to inject arbitrary SMTP commands for email spoofing and phishing attacks.

Nodemailer before version 8.0.8 disables TLS certificate verification in lib/fetch/index.js via rejectUnauthorized: false, allowing attackers to intercept OAuth2 token requests. Attackers in a machine-in-the-middle position can capture OAuth client secrets, refresh tokens, and access tokens transmitted over compromised HTTPS connections.

Nodemailer before version 8.0.9 fails to sanitize carriage return and line feed characters in list comment fields, allowing attackers to inject arbitrary message headers. An attacker with control over list.*.comment parameters can inject CRLF sequences to create additional headers in generated RFC822 messages, altering mail client behavior and message semantics.

Nodemailer before version 8.0.9 fails to enforce disableFileAccess and disableUrlAccess options during message normalization in jsonTransport. Attackers can read local files or fetch URLs by supplying path or href values in message content fields, bypassing intended access controls.

nodemailer before 9.0.1 fails to apply disableFileAccess and disableUrlAccess flags to message-level raw option, allowing authenticated attackers to read arbitrary files or perform server-side request forgery by supplying path or href properties. Attackers can exploit this by crafting raw messages with file paths or URLs that bypass the intended sandbox, with fetched content delivered in the outgoing message to attacker-controlled recipients.

Nodemailer before version 6.9.9 contains a regular expression denial of service vulnerability in email parsing when attachDataUrls parameter is set or processing embedded file attachments. Attackers can send specially crafted emails with malicious data URLs or embedded attachments to cause the event loop to hang and deny service.