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TI-2026-17561 Aliases CVE-2026-21859GHSA-8v65-47jx-7mfr

Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF)

Priority HIGH 65CWE-918Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. 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 1.28.0 and below have a Server-Side Request Forgery (SSRF) vulnerability in the /proxy endpoint, allowing attackers to make requests to internal network resources. The /proxy endpoint validates http:// and https:// schemes, but it does not block internal IP addresses, enabling attackers to access internal services and APIs. This vulnerability is limited to HTTP GET requests with minimal headers. The issue is fixed in version 1.28.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00813 57th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed mailpit (axllent): 1.28.1github.com/axllent/mailpit (Go): 1.28.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
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 1.28.11.28.1Patch availableCNA
—github.com/axllent/mailpit (Go)before 1.28.11.28.1Patch availableGHSA-8v65-47jx-7mfr
  • mailpit Vendoraxllent Affected before 1.28.1 Fixed in 1.28.1 Patch available CNA
  • github.com/axllent/mailpit (Go) Vendor— Affected before 1.28.1 Fixed in 1.28.1 Patch available GHSA-8v65-47jx-7mfr

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*before 1.28.1Vulnerableaxllent
  • cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:* Versions before 1.28.1 Vulnerable ·axllent

Remediation

  • Fix · CNA mailpit (axllent) Fixed in 1.28.1
  • Fix · GHSA-8v65-47jx-7mfr github.com/axllent/mailpit (Go) Fixed in 1.28.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-21859
  2. 2026-10-03 Alias added: GHSA-8v65-47jx-7mfr

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-2026-19194 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
  • TI-2026-19208 Mailpit Vulnerable to Server-Side Request Forgery (SSRF) via HTML Check API CVSS 3.1HIGH 7.5
See all 9 →

Sources

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