Read the docs
TI-2026-19208 Aliases CVE-2026-23845GHSA-6jxm-fv7w-rw5j

Mailpit Vulnerable to Server-Side Request Forgery (SSRF) via HTML Check API

Priority LOW 39CWE-918Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-918 and the CVSS impact.

Summary

Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (`/api/v1/message/{ID}/html-check`) is designed to analyze HTML emails for compatibility. During this process, the `inlineRemoteCSS()` function automatically downloads CSS files from external `<link rel="stylesheet" href="...">` tags to inline them for testing. Version 1.28.3 fixes the issue.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00431 37th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed mailpit (axllent): 1.28.3github.com/axllent/mailpit (Go): 1.28.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
axllentmailpitbefore 1.28.31.28.3Patch availableCNA
—github.com/axllent/mailpit (Go)before 1.28.31.28.3Patch availableGHSA-6jxm-fv7w-rw5j
  • mailpit Vendoraxllent Affected before 1.28.3 Fixed in 1.28.3 Patch available CNA
  • github.com/axllent/mailpit (Go) Vendor— Affected before 1.28.3 Fixed in 1.28.3 Patch available GHSA-6jxm-fv7w-rw5j

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*before 1.28.3Vulnerableaxllent
  • cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:* Versions before 1.28.3 Vulnerable ·axllent

Remediation

  • Fix · CNA mailpit (axllent) Fixed in 1.28.3
  • Fix · GHSA-6jxm-fv7w-rw5j github.com/axllent/mailpit (Go) Fixed in 1.28.3 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-23845
  2. 2026-10-03 Alias added: GHSA-6jxm-fv7w-rw5j

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • TI-2026-22161 Mailpit is Vulnerable to Server-Side Request Forgery (SSRF) via Link Check API CVSS 3.1HIGH 8.6
  • TI-2026-33452 Mailpit: Unauthenticated remote memory-exhaustion DoS via unlimited SMTP DATA and /api/v1/send body sizes CVSS 3.1HIGH 7.5
  • TI-2026-33450 Mailpit: Path traversal & arbitrary file write in mailpit dump --http via attacker-controlled message IDs CVSS 3.1HIGH 8.2
  • TI-2026-17561 Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF) CVSS 3.1MEDIUM 5.8
  • TI-2026-19194 Mailpit has SMTP Header Injection via Regex Bypass CVSS 3.1MEDIUM 5.3
  • TI-2026-33451 Race condition in axllent mailpit CVSS 3.1MEDIUM 5.9
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences