CVE-2026-123204

MEDIUM 4.3

Posta before v0.18.0 SSRF via Webhook URL

CVSS Score

4.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-918
Vendor	goposta
Product	posta
Published	Nov 5, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Affected Versions

goposta / posta

0 < v0.18.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/goposta/posta/issues/282 github.com: https://github.com/goposta/posta/pull/315 github.com: https://github.com/goposta/posta/commit/6bb376b55dcfdcb979040ed42c4bf57b99e4f46a github.com: https://github.com/goposta/posta/releases/tag/v0.18.0 github.com: https://github.com/goposta/posta/blob/8c3cb6f89c8a992329fac21491c38aed70d05c73/internal/services/webhook/dispatcher.go#L321-L338 vulncheck.com: https://www.vulncheck.com/advisories/posta-before-0.18.0-ssrf-via-webhook-url

Credits

George Chen jkaninda