Nodemailer: Quoted local-part can produce malformed envelope recipient through RFC 5322 comment parsing
## Summary Nodemailer's address parser can produce an unexpected recipient address when an RFC 5322 comment follows the domain of an address whose local-part is a quoted string. For example: ```text "user"@example.com(x)evil.com ``` is parsed as: ```text { address: "user@example.com evil.com", name: "" } ``` The resulting address therefore contains additional attacker-controlled domain text separated by a literal space. The parsed `.address` value is subsequently propagated into the SMTP envelope: ```text src/addressparser/index.ts ↓ recipient.address ↓ src/mime-node/index.ts ↓ envelope.to ``` The envelope construction uses the parsed address without another strict address validation step. This appears to be a variant of the RFC 5322 comment parsing issue addressed by GHSA-cc9r-2j5m-2m83, but it follows a different parser path when the local-part is quoted. ## Reproduction Input: ```text "user"@example.com(x)evil.com ``` Observed parser output: ```text address: "user@example.com evil.com" name: "" ``` A second example: ```text "a"@b.com(c)d.com(e)f.com ``` produces: ```text address: "a@b.com d.com f.com" name: "" ``` For comparison, the corresponding unquoted form: ```text user@example.com(x)evil.com ``` takes a different code path and is handled by the existing protection differently. ## Technical Details The issue is caused by different parsing behavior for quoted and unquoted local-parts. The quoted-local-part variant allows the comment-separated trailing domain atoms to r
GHSA-g57g-f23g-4646
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:GHSA-g57g-f23g-4646
nodemailer
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 10.0.9
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "9.1.0"
},
{
"fixed": "10.0.9"
}
]
}
],
"package": {
"name": "nodemailer",
"purl": "pkg:npm/nodemailer",
"ecosystem": "npm"
},
"database_specific": {
"source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-g57g-f23g-4646/GHSA-g57g-f23g-4646.json"
}
}
]- Related CVEs
- CVE-2026-100699
Source reference:
/aliases
Publisher severity
No explicit severity was provided.
- Event
- #33268 · Revision 1
- Added to Heist Feed
- Publisher date