CVE•Published 2026-01-19•1 article on news•6 live references•NVD data

CVE-2026-23829

Vulnerability data via CVEDB (Shodan)

CVSS v3.1

5.3

MEDIUM

EPSS percentile

Exploit Prediction Scoring System · top 30% of all CVEs

Description

Mailpit is an email testing tool and API for developers. Prior to version 1.28.3, Mailpit's SMTP server is vulnerable to Header Injection due to an insufficient Regular Expression used to validate `RCPT TO` and `MAIL FROM` addresses. An attacker can inject arbitrary SMTP headers (or corrupt existing ones) by including carriage return characters (`\r`) in the email address. This header injection occurs because the regex intended to filter control characters fails to exclude `\r` and `\n` when used inside a character class. Version 1.28.3 fixes this issue.

Timeline

Published 2026-01-19

External references

NVD MITRE Exploit-DB Sploitus trickest/cve VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-23829

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product + version

product:"Axllent Mailpit" version:"0.0.1"

Version-pinned fingerprint from NVD's first vulnerable CPE.

Shodan · banner/body mention

http.html:"Mailpit"

HTTP body or banner mentions "Mailpit" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-23829