Resource exhaustion in Axllent Mailpit
CVE-2026-45712
Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the screenshot/print proxy (/proxy?data=…) maintains a package-level assets map[string]MessageAssets cache, but reads the map without holding assetsMutex while a long-running cleanup goroutine and (re-entrant) CSS-rewriting code path concurrently write to it under the lock. When the unsynchronized read coincides with a synchronized write, Go's runtime raises fatal error: concurrent map read and map write — a runtime.throw that is not recoverable by http.Server's handler-panic recover. The whole Mailpit process exits, taking the SMTP, POP3 and HTTP listeners down with it. Version 1.30.0 contains a patch.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.003 (25.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Axllent Mailpit — versions < 1.30.0
Weakness classification (CWE)
References
- github.com/axllent/mailpit/security/advisories/GHSA-w4vj-r5pg-3722 (Exploit, Vendor Advisory)
- github.com/axllent/mailpit/releases/tag/v1.30.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-45712?
- CVE-2026-45712 is a medium-severity vulnerability in Axllent Mailpit, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 5.9/10. Published 2026-07-20.
- How severe is CVE-2026-45712?
- Medium severity. CVSS v3 base score is 5.9 out of 10.