CVE-2026-45712 — Mailpit: Concurrent map read & write in proxy CSS rewriter - remote unauth crash (fatal error: concurrent map read and map write)
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]MessageA…
Published: 2026-07-20 · CVSS: 5.9 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7