What’s Vulnerable › Vulnerabilities

CVE-2026-84697: Mailpit SSRF Deny List Bypass via Azure Metadata and IPv6 Prefix

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-02 · updated 2026-09-10
• Weakness: CWE-918

Description

Mailpit's IsInternalIP deny list function fails to block the Azure WireServer address 168.63.129.16 and the RFC 2765/6145 IPv4-translated IPv6 prefix, allowing server-side request forgery to internal destinations. Attackers can supply hostnames resolving to these addresses in message content to reach the link check API and proxy endpoint for accessing internal resources.

Affected products

• axllent mailpit: through 1.31.0

References

• https://github.com/axllent/mailpit
• https://github.com/axllent/mailpit/blob/v1.31.0/internal/tools/net.go
• https://github.com/axllent/mailpit/commit/a02821bf3424da9196e156c422370f4868a1dff2
• https://www.vulncheck.com/advisories/mailpit-ssrf-deny-list-bypass-via-azure-metadata-and-ipv6-prefix

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