CVE-2026-102471 Eclipse Foundation CVE debrief

Who should care

Defenders responsible for Eclipse Vert.x deployments, particularly those using the vertx-mail-client, should assess exposure and prioritize remediation to prevent potential email manipulation.

Why it matters

Defenders should care about this vulnerability as it allows an attacker to manipulate outgoing SMTP messages, potentially leading to email redirection or injection of malicious content. Affected versions of Eclipse Vert.x require verification and remediation to prevent exploitation.

• Potential manipulation of outgoing SMTP messages
• Injection of arbitrary headers or body content
• Possible redirection of email communications
• Verification of affected versions and remediation required

Technical summary

The vertx-mail-client in Eclipse Vert.x does not sanitize CR (r) or LF (n) characters in user-supplied email header names and values, allowing an attacker to inject arbitrary headers or prepend body content to outgoing SMTP messages. This vulnerability affects 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 weakness also affects MIME part metadata set via MailAttachment.setContentType(), setDisposition(), setDescription(), and setContentId(). An unauthenticated attacker who can control any header name, header value, or attachment metadata field passed to the mail client can exploit this to redirect email communications or inject malicious content.

Defensive priority

Defenders should prioritize verifying affected versions and applying vendor remediation to prevent potential email manipulation.

Recommended defensive actions

• Verify affected versions of Eclipse Vert.x and apply vendor remediation
• Review and sanitize user-supplied email header names and values
• Monitor outgoing SMTP messages for potential manipulation
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, affected versions, and potential impact. However, limited information is available on exploitation or victim impact. The vulnerability allows an attacker to inject arbitrary headers or prepend body content to outgoing SMTP messages. The vertx-mail-client does not sanitize CR (r) or LF (n) characters in user-supplied email header names and values. This weakness affects MIME part metadata set via MailAttachment.setContentType(), setDisposition(), setDescription(), and

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.