Mailpit: Thumbnail generation decodes unbounded image dimensions before scaling — GHSA-75MR-QW9X-3R39

Summary

## Summary Mailpit's thumbnail endpoint decodes attacker-supplied image attachments into a full raster before checking any decoded-pixel, dimension, or memory budget. A remote client that can store an email and reach the default web API can supply a compact high-dimension image, then request `/api/v1/message/{id}/part/{partID}/thumb` to force server-side memory and CPU work far larger than the encoded attachment…

Timeline

Published by source

2026-09-02

Risk context

• Reported severity or threat level: high.
• Reported CVSS score: 7.5 out of 10.
• Reported EPSS value: 0.00371.
• Review exposure for the affected product or family: go: github.com/axllent/mailpit.

Product

go: github.com/axllent/mailpit

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-75MR-QW9X-3R39

Source

GitHub

Vendor

GitHub

Published by source

2026-09-02

Last source activity

2026-09-02

Additional identifiers

CVE-2026-67446

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.