CVE-2026-123204

Medium

Description

Posta before v0.18.0 contains a server-side request forgery vulnerability that allows authenticated users with edit rights to make the backend send POST requests to internal destinations by creating webhooks with arbitrary URLs. Attackers can target loopback, private-network or cloud metadata addresses and read delivery status codes and error strings to probe internal hosts and ports.

SeverityMedium

CVSS4.3

Exploit probability—

ProductPosta

PublishedNov 5, 2026

First seenNov 5, 2026

Weakness typeCWE-918Server-side request forgery (SSRF)

How to fix

Update

goposta postav0.18.0 or later

Patches

Vendor advisories

github.com/goposta/posta/releases/tag/v0.18.0

Affected products

Product	Affected versions	Fixed in
goposta posta	v < v0.18.0	v0.18.0

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