CVE-2026-123204: goposta posta

Posta before v0.18.0 SSRF via Webhook URL

CVSS 5.3 Medium

Published by the CVE Program (CNA: VulnCheck) at 5 Nov 2026, 18:16 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
goposta	posta pkg:golang/github.com/goposta/posta	affected before v0.18.0 custom Other versions: unaffected

Identifiers

CVE-2026-123204

CNA

VulnCheck

Weakness (CWE)

CWE-918

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
5.3	Medium	4.0	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N	CNA (VulnCheck)Used for this record
4.3	Medium	3.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N	CNA (VulnCheck)

CISA KEV Not listed.
EPSS No score.

Timeline

5 Nov 2026, 18:16 UTC Confirmed by the CVE List
5 Nov 2026, 18:19 UTC First seen by agentprime
5 Nov 2026, 19:17 UTC Confirmed by NVD

Sources

References from the CNA

github.com/goposta/posta/issues/282 issue-tracking
github.com/goposta/posta/pull/315 patchissue-tracking
github.com/goposta/posta/commit/6bb376b55dcfdcb979040ed42c4bf57b99e4f46a patch
github.com/goposta/posta/releases/tag/v0.18.0 release-notes
github.com/goposta/posta/blob/8c3cb6f89c8a992329fac21491c38aed70d05c73/internal/services/webhook/dispatcher.go#L321-L338 technical-description
www.vulncheck.com/advisories/posta-before-0.18.0-ssrf-via-webhook-url third-party-advisory

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.