SSRF in Goposta Posta
CVE-2026-123204
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
Published .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/goposta/posta/blob/8c3cb6f89c8a992329fac21491c38aed70d05c73/internal… (technical-description)
- github.com/goposta/posta/commit/6bb376b55dcfdcb979040ed42c4bf57b99e4f46a (patch)
- github.com/goposta/posta/issues/282 (issue-tracking)
- github.com/goposta/posta/pull/315 (issue-tracking, patch)
- posta v0.18.0 Release Notes (release-notes)
- VulnCheck Advisory: Posta before v0.18.0 SSRF via Webhook URL (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123204?
- CVE-2026-123204 is a medium-severity vulnerability in Goposta Posta, classified under Server-Side Request Forgery (SSRF). CVSS score: 4.3/10. Published 2026-11-05.
- How severe is CVE-2026-123204?
- Medium severity. CVSS v3 base score is 4.3 out of 10.