CVE Catalog

CVE-2026-102471

MediumCVSS 6.9
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.32%

24th percentile - higher than 24% of all known CVEs

Summary

In Eclipse Vert.x versions [4.0.0, 4.5.34], [5.0.0, 5.0.12], [5.1.0, 5.1.9], and 5.2.0, the vertx-mail-client does not sanitize CR/LF characters in user-supplied email header names and values before writing them to the SMTP DATA section. Injecting CR/LF sequences allows adding arbitrary headers (e.g., Bcc, Reply-To) or prepending body content; the same weakness affects MIME part metadata.

Risk Assessment

An unauthenticated attacker controlling any header field or attachment metadata can redirect email copies, spoof headers, or tamper with message structure. This can lead to data leakage or phishing.

Recommendation

Upgrade Eclipse Vert.x to a version containing the fix (above 4.5.34, 5.0.12, 5.1.9, or 5.2.0). Until then, validate and sanitize all input reaching email headers.

Other vulnerabilities in Eclipse Vert.x

See all
Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS