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.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 10.4.1
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 30/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.3/10CVSS 8.3
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 10.4.1.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
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.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- nodemailer nodemailer
From 3.0.0 · fixed in 10.4.1
Evidence 7
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 4
- Patch
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-125755
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: cve.now feed data
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: vulncheck.com, github.com
Which versions are affected by CVE-2026-125755?
nodemailer: from 3.0.0 before 10.4.1.Source: cve.now feed data
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: vulncheck.com, github.com
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: vulncheck.com, github.com