Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Mailpit versions 1.28.3 up to but not including 1.30.0 are affected. The HTML check endpoint's CSS downloader lacks the IP filtering dialer used by other SSRF-protected handlers, so it can reach loopback, private, link-local (including cloud metadata) and CGNAT addresses, including via redirects. An attacker who can send an HTML email to Mailpit and reach its API can trigger this without authentication in the default configuration. Upgrade to Mailpit 1.30.0 or later. The source gives no other workaround.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 5.8 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0032, the 24th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:46 UTC First seen by agentprime
- 31 Oct 2026, 14:46 UTC Confirmed by OSV