CVE-2026-45711: Mailpit: Path traversal & arbitrary file write in mailpit dump --http via attacker-controlled message IDs

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-07-20 · updated 2026-10-24
Weakness: CWE-22

Description

Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the mailpit dump --http <base-url> <out-dir> sub-command downloads every message from a remote Mailpit instance and writes each one as <id>.eml inside the user-supplied output directory. The message ID field is taken verbatim from the JSON response of the remote server and concatenated into the output path with path.Join, which silently normalizes `..` segments. A malicious HTTP server impersonating Mailpit can therefore make mailpit dump write attacker-controlled bytes to any path the running user can write, fully outside the intended output directory. Version 1.30.0 contains a patch.

Affected products

axllent mailpit: before 1.30.0 — fixed in 1.30.0

How to fix

Upgrade to a fixed version: axllent mailpit 1.30.0. Check the vendor advisory for mitigations.

References

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