EXECUTIVE SUMMARY:
Mailpit is affected by two high-severity vulnerabilities that can allow remote attackers to exhaust server resources and cause denial-of-service conditions. One vulnerability is caused by the SMTP command parser buffering arbitrarily long command lines before applying protocol validation, allowing an unauthenticated attacker to consume excessive memory through oversized SMTP commands. The other affects thumbnail generation, where attacker-controlled images are fully decoded into memory before dimension or resource limits are checked, enabling CPU and memory exhaustion through specially crafted high-dimension images.[/subscribe_to_unlock_form]
EXECUTIVE SUMMARY:
Mailpit is affected by two high-severity vulnerabilities that can allow remote attackers to exhaust server resources and cause denial-of-service conditions. One vulnerability is caused by the SMTP command parser buffering arbitrarily long command lines before applying protocol validation, allowing an unauthenticated attacker to consume excessive memory through oversized SMTP commands. The other affects thumbnail generation, where attacker-controlled images are fully decoded into memory before dimension or resource limits are checked, enabling CPU and memory exhaustion through specially crafted high-dimension images.[emaillocker id="1283"]
CVE-2026-67446 (CVSS 7.5 — High): A vulnerability was discovered in thumbnail generation where unbounded image dimensions are decoded before scaling, allowing an attacker to potentially cause a denial of service or execute arbitrary code. An attacker with network access can exploit this vulnerability.
CVE-2026-67445 (CVSS 7.5 — High): A buffer overflow issue exists in the SMTP command parser where unbounded command lines are buffered before syntax rejection, allowing an attacker to potentially execute arbitrary code.
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REFERENCES:
The following reports contain further technical details:
https://github.com/advisories/GHSA-75mr-qw9x-3r39
https://github.com/advisories/GHSA-w878-pj84-3j5v