CVE-2026-102471 (GCVE-0-2026-102471)
Vulnerability from cvelistv5 – Published: 2026-10-14 18:50 – Updated: 2026-10-14 19:49
VLAI
EPSS
VEX
Title
CRLF header injection in vertx-mail-client allows manipulation of outgoing SMTP messages
Summary
In Eclipse Vert.x versions [4.0.0, 4.5.34] or [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], the vertx-mail-client does not sanitize CR (\r) or LF (\n) characters in user-supplied email header names and values before writing them into the SMTP DATA section. A CR/LF sequence embedded in a name or value passed to MailMessage.addHeader(), MailMessage.setHeaders(), MailAttachment.addHeader(), or MailAttachment.setHeaders() is written verbatim to the wire, allowing an attacker to inject arbitrary headers (e.g. Bcc, Reply-To, Content-Type) or prepend body content to the outgoing message.
The same weakness affects MIME part metadata set via MailAttachment.setContentType(), setDisposition(), setDescription(), and setContentId(), which are written directly into MIME part headers without validation.
A secondary weakness in Utils.mustEncode(char) additionally allows a bare LF in a From display-name to bypass Q-encoding and reach the wire unchanged.
An unauthenticated attacker who can control any header name, header value, or attachment metadata field passed to the mail client (for example via a web form or API that feeds into MailMessage) can exploit this to redirect email copies, spoof headers, or tamper with message structure.
The impacted component is io.vertx:vertx-mail-client.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-14 19:48 UTC
CWE
- CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Eclipse Foundation | Eclipse Vert.x |
Affected:
4.0.0 , ≤ 4.5.34
(semver)
Affected: 5.0.0 , ≤ 5.0.12 (semver) Affected: 5.1.0 , ≤ 5.1.9 (semver) Affected: 5.2.0 (semver) |
guessed |
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